<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.liquidityservices.com/role/BusinessRealignmentExpenses" xlink:href="lqdt-20180630.xsd#BusinessRealignmentExpenses" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/BusinessRealignmentExpensesNarrativeDetails" xlink:href="lqdt-20180630.xsd#BusinessRealignmentExpensesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/BusinessRealignmentExpensesRestructuringRelatedCostsDetails" xlink:href="lqdt-20180630.xsd#BusinessRealignmentExpensesRestructuringRelatedCostsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/BusinessRealignmentExpensesTables" xlink:href="lqdt-20180630.xsd#BusinessRealignmentExpensesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/ConsolidatedBalanceSheets" xlink:href="lqdt-20180630.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="lqdt-20180630.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/DefinedBenefitPensionPlan" xlink:href="lqdt-20180630.xsd#DefinedBenefitPensionPlan" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/DefinedBenefitPensionPlanNetPeriodicBenefitDetails" xlink:href="lqdt-20180630.xsd#DefinedBenefitPensionPlanNetPeriodicBenefitDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/DefinedBenefitPensionPlanTables" xlink:href="lqdt-20180630.xsd#DefinedBenefitPensionPlanTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/DocumentAndEntityInformation" xlink:href="lqdt-20180630.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/FairValueMeasurement" xlink:href="lqdt-20180630.xsd#FairValueMeasurement" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/FairValueMeasurementChangeInLevel3AssetsDetails" xlink:href="lqdt-20180630.xsd#FairValueMeasurementChangeInLevel3AssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/FairValueMeasurementNarrativeDetails" xlink:href="lqdt-20180630.xsd#FairValueMeasurementNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/FairValueMeasurementTables" xlink:href="lqdt-20180630.xsd#FairValueMeasurementTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/Goodwill" xlink:href="lqdt-20180630.xsd#Goodwill" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/GoodwillAdjustmentsDetails" xlink:href="lqdt-20180630.xsd#GoodwillAdjustmentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/GoodwillTables" xlink:href="lqdt-20180630.xsd#GoodwillTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/Guarantees" xlink:href="lqdt-20180630.xsd#Guarantees" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/GuaranteesNarrativeDetails" xlink:href="lqdt-20180630.xsd#GuaranteesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/IncomeTaxes" xlink:href="lqdt-20180630.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/IncomeTaxesNarrativeDetails" xlink:href="lqdt-20180630.xsd#IncomeTaxesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/IntangibleAssets" xlink:href="lqdt-20180630.xsd#IntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/IntangibleAssetsAmortizationDetails" xlink:href="lqdt-20180630.xsd#IntangibleAssetsAmortizationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/IntangibleAssetsCarryingAmountDetails" xlink:href="lqdt-20180630.xsd#IntangibleAssetsCarryingAmountDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/IntangibleAssetsNarrativeDetails" xlink:href="lqdt-20180630.xsd#IntangibleAssetsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/IntangibleAssetsTables" xlink:href="lqdt-20180630.xsd#IntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/LegalProceedings" xlink:href="lqdt-20180630.xsd#LegalProceedings" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/LegalProceedingsNarrativeDetails" xlink:href="lqdt-20180630.xsd#LegalProceedingsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/Organization" xlink:href="lqdt-20180630.xsd#Organization" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/OrganizationNarrativeDetails" xlink:href="lqdt-20180630.xsd#OrganizationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SegmentInformation" xlink:href="lqdt-20180630.xsd#SegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SegmentInformationNarrativeDetails" xlink:href="lqdt-20180630.xsd#SegmentInformationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SegmentInformationReconciliationOfRevenueDetails" xlink:href="lqdt-20180630.xsd#SegmentInformationReconciliationOfRevenueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SegmentInformationTables" xlink:href="lqdt-20180630.xsd#SegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SignificantContracts" xlink:href="lqdt-20180630.xsd#SignificantContracts" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SignificantContractsNarrativeDetails" xlink:href="lqdt-20180630.xsd#SignificantContractsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/StockholdersEquity" xlink:href="lqdt-20180630.xsd#StockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/StockholdersEquity2006PlanActivityDetails" xlink:href="lqdt-20180630.xsd#StockholdersEquity2006PlanActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/StockholdersEquityNarrativeDetails" xlink:href="lqdt-20180630.xsd#StockholdersEquityNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/StockholdersEquityRestrictedShareActivityDetails" xlink:href="lqdt-20180630.xsd#StockholdersEquityRestrictedShareActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/StockholdersEquityTables" xlink:href="lqdt-20180630.xsd#StockholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SubsequentEvent" xlink:href="lqdt-20180630.xsd#SubsequentEvent" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SubsequentEventNarrativeDetails" xlink:href="lqdt-20180630.xsd#SubsequentEventNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="lqdt-20180630.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesEarningsPerShareDetails" xlink:href="lqdt-20180630.xsd#SummaryOfSignificantAccountingPoliciesEarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:href="lqdt-20180630.xsd#SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="lqdt-20180630.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="lqdt-20180630.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/UnauditedConsolidatedStatementsOfCashFlows" xlink:href="lqdt-20180630.xsd#UnauditedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/UnauditedConsolidatedStatementsOfComprehensiveLoss" xlink:href="lqdt-20180630.xsd#UnauditedConsolidatedStatementsOfComprehensiveLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liquidityservices.com/role/UnauditedConsolidatedStatementsOfOperations" xlink:href="lqdt-20180630.xsd#UnauditedConsolidatedStatementsOfOperations" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/BusinessRealignmentExpenses" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/BusinessRealignmentExpensesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_621815A04B68F05BD4E1B989E8D3A3D7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_621815A04B68F05BD4E1B989E8D3A3D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_FD1D88C21D9A51158348B989E8D3A7CA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_621815A04B68F05BD4E1B989E8D3A3D7" xlink:to="loc_us-gaap_SegmentDomain_FD1D88C21D9A51158348B989E8D3A7CA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_FD1D88C21D9A51158348B989E8D3A7CA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_621815A04B68F05BD4E1B989E8D3A3D7" xlink:to="loc_us-gaap_SegmentDomain_FD1D88C21D9A51158348B989E8D3A7CA" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_CAGMember" xlink:label="loc_lqdt_CAGMember_E0C405AE9C74DED69666B989E8D3F6FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_FD1D88C21D9A51158348B989E8D3A7CA" xlink:to="loc_lqdt_CAGMember_E0C405AE9C74DED69666B989E8D3F6FC" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_IronDirectMember" xlink:label="loc_lqdt_IronDirectMember_C7A48328404FBB3EC065B989E8D4327B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_FD1D88C21D9A51158348B989E8D3A7CA" xlink:to="loc_lqdt_IronDirectMember_C7A48328404FBB3EC065B989E8D4327B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_D4D07AA5E22CF30A3FA8B989E8D42EDA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_D4D07AA5E22CF30A3FA8B989E8D42EDA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_D4D07AA5E22CF30A3FA8B989E8D42EDA" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_D4D07AA5E22CF30A3FA8B989E8D42EDA" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_1C624DC99375323F2BBFB989E8D42690" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:to="loc_us-gaap_EmployeeSeveranceMember_1C624DC99375323F2BBFB989E8D42690" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_LegalandAdministrativeCostsMember" xlink:label="loc_lqdt_LegalandAdministrativeCostsMember_350BC9DA260159986194B989E8D5BA57" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:to="loc_lqdt_LegalandAdministrativeCostsMember_350BC9DA260159986194B989E8D5BA57" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_OccupancyAndContractCostsMember" xlink:label="loc_lqdt_OccupancyAndContractCostsMember_B94D95FADA3AEB78949FB989E8D528E9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:to="loc_lqdt_OccupancyAndContractCostsMember_B94D95FADA3AEB78949FB989E8D528E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_FA0C08D53501DDD433A8B989E8D5035C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_FA0C08D53501DDD433A8B989E8D5035C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_908FAC7E0FDFBDFC4B39B989E8D53806" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_908FAC7E0FDFBDFC4B39B989E8D53806" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_TechnologyandOperationsMember" xlink:label="loc_lqdt_TechnologyandOperationsMember_59E008F021A92B0295F5B989E8D52B17" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_31D07128F4802AEB8D21B989E8D4316E" xlink:to="loc_lqdt_TechnologyandOperationsMember_59E008F021A92B0295F5B989E8D52B17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringPlanAxis" xlink:label="loc_us-gaap_RestructuringPlanAxis_8036EEB4A021F1AB2D08B989E8D5C0C0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_RestructuringPlanAxis_8036EEB4A021F1AB2D08B989E8D5C0C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:label="loc_us-gaap_RestructuringPlanDomain_437D5ED5517442D35172B989E8D6AD59_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_8036EEB4A021F1AB2D08B989E8D5C0C0" xlink:to="loc_us-gaap_RestructuringPlanDomain_437D5ED5517442D35172B989E8D6AD59_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringPlanDomain" xlink:label="loc_us-gaap_RestructuringPlanDomain_437D5ED5517442D35172B989E8D6AD59" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_8036EEB4A021F1AB2D08B989E8D5C0C0" xlink:to="loc_us-gaap_RestructuringPlanDomain_437D5ED5517442D35172B989E8D6AD59" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_SeveranceAgreementMember" xlink:label="loc_lqdt_SeveranceAgreementMember_BD74279A8F8FD26D52EFB989E8D6F0AA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_437D5ED5517442D35172B989E8D6AD59" xlink:to="loc_lqdt_SeveranceAgreementMember_BD74279A8F8FD26D52EFB989E8D6F0AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4A3156876FB1EDFCEA17B989E8D69777" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4A3156876FB1EDFCEA17B989E8D69777" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_A57C17D0C0F2C04E03B8B989E8D6A1CF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4A3156876FB1EDFCEA17B989E8D69777" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_A57C17D0C0F2C04E03B8B989E8D6A1CF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_A57C17D0C0F2C04E03B8B989E8D6A1CF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4A3156876FB1EDFCEA17B989E8D69777" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_A57C17D0C0F2C04E03B8B989E8D6A1CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ContractBasedIntangibleAssetsMember" xlink:label="loc_us-gaap_ContractBasedIntangibleAssetsMember_44BE75C0DF7C386CB12FB989E8D7F01C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_A57C17D0C0F2C04E03B8B989E8D6A1CF" xlink:to="loc_us-gaap_ContractBasedIntangibleAssetsMember_44BE75C0DF7C386CB12FB989E8D7F01C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F348C806BBC9C5889F30B989E8D7CAB0" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F348C806BBC9C5889F30B989E8D7CAB0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94765FAD36FDB7296475B989E8D7D1DF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F348C806BBC9C5889F30B989E8D7CAB0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94765FAD36FDB7296475B989E8D7D1DF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94765FAD36FDB7296475B989E8D7D1DF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_F348C806BBC9C5889F30B989E8D7CAB0" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94765FAD36FDB7296475B989E8D7D1DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_61227BDFE600AD5AC4AAB989E8D79C90" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94765FAD36FDB7296475B989E8D7D1DF" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_61227BDFE600AD5AC4AAB989E8D79C90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_BFDC1271D8876DD06B4AB989E8D818FE" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_ConsolidationItemsAxis_BFDC1271D8876DD06B4AB989E8D818FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_61039F664B192CA7C47EB989E8D8ED3D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_BFDC1271D8876DD06B4AB989E8D818FE" xlink:to="loc_us-gaap_ConsolidationItemsDomain_61039F664B192CA7C47EB989E8D8ED3D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_61039F664B192CA7C47EB989E8D8ED3D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_BFDC1271D8876DD06B4AB989E8D818FE" xlink:to="loc_us-gaap_ConsolidationItemsDomain_61039F664B192CA7C47EB989E8D8ED3D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_353F727D7BD39BACE457B989E8D8825E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_61039F664B192CA7C47EB989E8D8ED3D" xlink:to="loc_us-gaap_CorporateNonSegmentMember_353F727D7BD39BACE457B989E8D8825E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_2D9EAB1E3EC2B9B260D7B989E8D8360F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_StatementGeographicalAxis_2D9EAB1E3EC2B9B260D7B989E8D8360F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_C1A9C83119A5A1EE49B5B989E8D9E319_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_2D9EAB1E3EC2B9B260D7B989E8D8360F" xlink:to="loc_us-gaap_SegmentGeographicalDomain_C1A9C83119A5A1EE49B5B989E8D9E319_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_C1A9C83119A5A1EE49B5B989E8D9E319" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_2D9EAB1E3EC2B9B260D7B989E8D8360F" xlink:to="loc_us-gaap_SegmentGeographicalDomain_C1A9C83119A5A1EE49B5B989E8D9E319" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_BethesdaMarylandMember" xlink:label="loc_lqdt_BethesdaMarylandMember_3FFF9D684D6C442C989CB989E8D9E263" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_C1A9C83119A5A1EE49B5B989E8D9E319" xlink:to="loc_lqdt_BethesdaMarylandMember_3FFF9D684D6C442C989CB989E8D9E263" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/stpr/2011/stpr-2011-01-31.xsd#stpr_DC" xlink:label="loc_stpr_DC_CAAFA907AF5E61ADAE18B989E8D902CB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_C1A9C83119A5A1EE49B5B989E8D9E319" xlink:to="loc_stpr_DC_CAAFA907AF5E61ADAE18B989E8D902CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_3088BCE02216237CED73B989E8D97D7F" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_3088BCE02216237CED73B989E8D97D7F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_96E468AE8151E25C7791B989E8D98747_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_3088BCE02216237CED73B989E8D97D7F" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_96E468AE8151E25C7791B989E8D98747_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_96E468AE8151E25C7791B989E8D98747" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_3088BCE02216237CED73B989E8D97D7F" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_96E468AE8151E25C7791B989E8D98747" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherOperatingIncomeExpenseMember" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseMember_AB14BD3CB2604C6E08ADB989E8DA79B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_96E468AE8151E25C7791B989E8D98747" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseMember_AB14BD3CB2604C6E08ADB989E8DA79B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis" xlink:label="loc_us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_8B6284FBF1798F7589C5B989E8DAE76C" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_68A49DF31AA0ACFDDE5BB989E8D3FD4C" xlink:to="loc_us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_8B6284FBF1798F7589C5B989E8DAE76C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:label="loc_us-gaap_MortgageLoansOnRealEstateNamePropertyTypeDomain_97C54D9029ADFD83303EB989E8DAF7D4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_8B6284FBF1798F7589C5B989E8DAE76C" xlink:to="loc_us-gaap_MortgageLoansOnRealEstateNamePropertyTypeDomain_97C54D9029ADFD83303EB989E8DAF7D4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MortgageLoansOnRealEstateNamePropertyTypeDomain" xlink:label="loc_us-gaap_MortgageLoansOnRealEstateNamePropertyTypeDomain_97C54D9029ADFD83303EB989E8DAF7D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_8B6284FBF1798F7589C5B989E8DAE76C" xlink:to="loc_us-gaap_MortgageLoansOnRealEstateNamePropertyTypeDomain_97C54D9029ADFD83303EB989E8DAF7D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OfficeBuildingMember" xlink:label="loc_us-gaap_OfficeBuildingMember_B1EEE31D8BBB496A1C77B989E8DA0FAF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MortgageLoansOnRealEstateNamePropertyTypeDomain_97C54D9029ADFD83303EB989E8DAF7D4" xlink:to="loc_us-gaap_OfficeBuildingMember_B1EEE31D8BBB496A1C77B989E8DA0FAF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCosts" xlink:label="loc_us-gaap_RestructuringCosts_CB7BCFFA9EC2CA14AEBCB989E8DBDF0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_RestructuringCosts_CB7BCFFA9EC2CA14AEBCB989E8DBDF0A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaap_AssetImpairmentCharges_9D31C863D37ED9F9E468B989E8DBD7F5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_AssetImpairmentCharges_9D31C863D37ED9F9E468B989E8DBD7F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_829688B35970969205CFB989E8DB8581" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_829688B35970969205CFB989E8DB8581" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_2BA616AC03DFA7A3374AB989E8DBB283" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_2BA616AC03DFA7A3374AB989E8DBB283" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_9F66C60CB707B3E8A460B989E8DCB215" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_9F66C60CB707B3E8A460B989E8DCB215" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AreaOfRealEstateProperty" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_08CDB689581494914B85B989E8DC93D9" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_AreaOfRealEstateProperty_08CDB689581494914B85B989E8DC93D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LossOnContractTermination" xlink:label="loc_us-gaap_LossOnContractTermination_8D16625123565606C2ABB989E8DC9C22" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_LossOnContractTermination_8D16625123565606C2ABB989E8DC9C22" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_PaymentonContractLossTermination" xlink:label="loc_lqdt_PaymentonContractLossTermination_D924A8F09D4605EA7486B989E8DCA1A9" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_lqdt_PaymentonContractLossTermination_D924A8F09D4605EA7486B989E8DCA1A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_76C54A084546143A2639B989E8DC175E" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_RestructuringCharges_76C54A084546143A2639B989E8DC175E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_2FF9C7E694C9BBC64C40B989E8DC38F1" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_AB7C8B60C69C0479839AB989E8DB7417" xlink:to="loc_us-gaap_RestructuringReserve_2FF9C7E694C9BBC64C40B989E8DC38F1" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/BusinessRealignmentExpensesRestructuringRelatedCostsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_9BF18E462CF5118F122E8AE04B16986D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63356BC0F0AA9FD965328AE04B138CA2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_9BF18E462CF5118F122E8AE04B16986D" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63356BC0F0AA9FD965328AE04B138CA2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_879D9C05E5C9224CE4CF8AE04B14212A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63356BC0F0AA9FD965328AE04B138CA2" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_879D9C05E5C9224CE4CF8AE04B14212A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_6EDEAECB9FF763CF811D8AE04B1566B8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_879D9C05E5C9224CE4CF8AE04B14212A" xlink:to="loc_us-gaap_SegmentDomain_6EDEAECB9FF763CF811D8AE04B1566B8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_6EDEAECB9FF763CF811D8AE04B1566B8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_879D9C05E5C9224CE4CF8AE04B14212A" xlink:to="loc_us-gaap_SegmentDomain_6EDEAECB9FF763CF811D8AE04B1566B8" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_CAGMember" xlink:label="loc_lqdt_CAGMember_6D5B1AB565B43F522CEF8AE04B152F7A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6EDEAECB9FF763CF811D8AE04B1566B8" xlink:to="loc_lqdt_CAGMember_6D5B1AB565B43F522CEF8AE04B152F7A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_085ECB483D96DF35FC368AE04B14A7E4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63356BC0F0AA9FD965328AE04B138CA2" xlink:to="loc_us-gaap_ConsolidationItemsAxis_085ECB483D96DF35FC368AE04B14A7E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_223BFC8A033365870DE98AE04B1424DD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_085ECB483D96DF35FC368AE04B14A7E4" xlink:to="loc_us-gaap_ConsolidationItemsDomain_223BFC8A033365870DE98AE04B1424DD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_223BFC8A033365870DE98AE04B1424DD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_085ECB483D96DF35FC368AE04B14A7E4" xlink:to="loc_us-gaap_ConsolidationItemsDomain_223BFC8A033365870DE98AE04B1424DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_8999F2F78D042DDC6CB98AE04B149C10" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_223BFC8A033365870DE98AE04B1424DD" xlink:to="loc_us-gaap_CorporateNonSegmentMember_8999F2F78D042DDC6CB98AE04B149C10" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_0676A9E1678A3FE557858AE04B15C1E3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63356BC0F0AA9FD965328AE04B138CA2" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_0676A9E1678A3FE557858AE04B15C1E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_775B249B8356F22F3A048AE04B1664C7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_0676A9E1678A3FE557858AE04B15C1E3" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_775B249B8356F22F3A048AE04B1664C7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_775B249B8356F22F3A048AE04B1664C7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_0676A9E1678A3FE557858AE04B15C1E3" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_775B249B8356F22F3A048AE04B1664C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_47B3E06691C3A4E0645C8AE04B16F440" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_775B249B8356F22F3A048AE04B1664C7" xlink:to="loc_us-gaap_EmployeeSeveranceMember_47B3E06691C3A4E0645C8AE04B16F440" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_OccupancyCostMember" xlink:label="loc_lqdt_OccupancyCostMember_6F64D15593F4DF9F62EE8AE04B160EB1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_775B249B8356F22F3A048AE04B1664C7" xlink:to="loc_lqdt_OccupancyCostMember_6F64D15593F4DF9F62EE8AE04B160EB1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringReserveRollForward" xlink:label="loc_us-gaap_RestructuringReserveRollForward_C3DB90925A2D337DE1D28AE04B164226" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_9BF18E462CF5118F122E8AE04B16986D" xlink:to="loc_us-gaap_RestructuringReserveRollForward_C3DB90925A2D337DE1D28AE04B164226" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_39D81C596A3C9A69D0378AE04B17F77E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_C3DB90925A2D337DE1D28AE04B164226" xlink:to="loc_us-gaap_RestructuringReserve_39D81C596A3C9A69D0378AE04B17F77E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_77439F12CBBF635283B98AE04B1746BE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_C3DB90925A2D337DE1D28AE04B164226" xlink:to="loc_us-gaap_RestructuringCharges_77439F12CBBF635283B98AE04B1746BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsForRestructuring" xlink:label="loc_us-gaap_PaymentsForRestructuring_45A107E2B7B76E419D4E8AE04B1724AF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_C3DB90925A2D337DE1D28AE04B164226" xlink:to="loc_us-gaap_PaymentsForRestructuring_45A107E2B7B76E419D4E8AE04B1724AF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/BusinessRealignmentExpensesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/ConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/DefinedBenefitPensionPlan" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/DefinedBenefitPensionPlanNetPeriodicBenefitDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/DefinedBenefitPensionPlanTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/FairValueMeasurement" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/FairValueMeasurementChangeInLevel3AssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_FBDB63F4601A1CC53E918FFFE0DE3C8E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_FC2FB3A9AE700D7792F58FFFE0D5A53C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_FBDB63F4601A1CC53E918FFFE0DE3C8E" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_FC2FB3A9AE700D7792F58FFFE0D5A53C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_CBDA8BF5A730071042948FFFE0D5A438" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_FC2FB3A9AE700D7792F58FFFE0D5A53C" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_CBDA8BF5A730071042948FFFE0D5A438" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_37D0D17F298BC43545B18FFFE0D55E03_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_CBDA8BF5A730071042948FFFE0D5A438" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_37D0D17F298BC43545B18FFFE0D55E03_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_37D0D17F298BC43545B18FFFE0D55E03" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_CBDA8BF5A730071042948FFFE0D5A438" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_37D0D17F298BC43545B18FFFE0D55E03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_C812C79E1D985FBF00FA8FFFE0DB4E6F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_37D0D17F298BC43545B18FFFE0D55E03" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_C812C79E1D985FBF00FA8FFFE0DB4E6F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_26F8BB0B4E96FDEB79398FFFE0DCC5E1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_FC2FB3A9AE700D7792F58FFFE0D5A53C" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_26F8BB0B4E96FDEB79398FFFE0DCC5E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6485A29ACEF0D9DA6AD28FFFE0DCBAC8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_26F8BB0B4E96FDEB79398FFFE0DCC5E1" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6485A29ACEF0D9DA6AD28FFFE0DCBAC8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6485A29ACEF0D9DA6AD28FFFE0DCBAC8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_26F8BB0B4E96FDEB79398FFFE0DCC5E1" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6485A29ACEF0D9DA6AD28FFFE0DCBAC8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_50530F35C3D2D3BDA2638FFFE0DD6843" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6485A29ACEF0D9DA6AD28FFFE0DCBAC8" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_50530F35C3D2D3BDA2638FFFE0DD6843" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_6C948B51952826CB10478FFFE0DECC66" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_FBDB63F4601A1CC53E918FFFE0DE3C8E" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_6C948B51952826CB10478FFFE0DECC66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_6A02BB91576B0BA1040F8FFFE0DE85C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_6C948B51952826CB10478FFFE0DECC66" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_6A02BB91576B0BA1040F8FFFE0DE85C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_E48D96AC3517AB1926528FFFE0DF5E0D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_6C948B51952826CB10478FFFE0DECC66" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_E48D96AC3517AB1926528FFFE0DF5E0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_A64A03F610B5B27AF11E8FFFE0DF30C6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_6C948B51952826CB10478FFFE0DECC66" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_A64A03F610B5B27AF11E8FFFE0DF30C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_5D51DA90F656371E3E518FFFE0DFC643" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_6C948B51952826CB10478FFFE0DECC66" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_5D51DA90F656371E3E518FFFE0DFC643" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/FairValueMeasurementNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8469FC73C048DFD5D5ED8FFFE0F37748" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0C1F7C27343D0CBB986F8FFFE0F09847" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8469FC73C048DFD5D5ED8FFFE0F37748" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0C1F7C27343D0CBB986F8FFFE0F09847" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F630E64974E281A3F4178FFFE0F1967E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0C1F7C27343D0CBB986F8FFFE0F09847" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F630E64974E281A3F4178FFFE0F1967E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_36CF3EC0B42D41AAAA068FFFE0F17F6A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F630E64974E281A3F4178FFFE0F1967E" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_36CF3EC0B42D41AAAA068FFFE0F17F6A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_36CF3EC0B42D41AAAA068FFFE0F17F6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F630E64974E281A3F4178FFFE0F1967E" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_36CF3EC0B42D41AAAA068FFFE0F17F6A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_EEF77A834C74FF175FE58FFFE0F20935" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_36CF3EC0B42D41AAAA068FFFE0F17F6A" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_EEF77A834C74FF175FE58FFFE0F20935" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0FE4487A9ED17614621A8FFFE0F2D73B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_0C1F7C27343D0CBB986F8FFFE0F09847" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0FE4487A9ED17614621A8FFFE0F2D73B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8981B5772E4BF5961A758FFFE0F2EEA2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0FE4487A9ED17614621A8FFFE0F2D73B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8981B5772E4BF5961A758FFFE0F2EEA2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8981B5772E4BF5961A758FFFE0F2EEA2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0FE4487A9ED17614621A8FFFE0F2D73B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8981B5772E4BF5961A758FFFE0F2EEA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_517DDF62A0C778DEFD6A8FFFE0F26AB6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8981B5772E4BF5961A758FFFE0F2EEA2" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_517DDF62A0C778DEFD6A8FFFE0F26AB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_7C901249A43992059BF88FFFE0F3166F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8981B5772E4BF5961A758FFFE0F2EEA2" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_7C901249A43992059BF88FFFE0F3166F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_B8A8CCAA821F7A72BB6B8FFFE0F3E870" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8981B5772E4BF5961A758FFFE0F2EEA2" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_B8A8CCAA821F7A72BB6B8FFFE0F3E870" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_C200694B1E4245AE04CC8FFFE0F44FDF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8469FC73C048DFD5D5ED8FFFE0F37748" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_C200694B1E4245AE04CC8FFFE0F44FDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_EE9C5E7DD10B74C42D0E8FFFE0F4900E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8469FC73C048DFD5D5ED8FFFE0F37748" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_EE9C5E7DD10B74C42D0E8FFFE0F4900E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_1481CD67DF9DFC7EF2358FFFE0F410DB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_8469FC73C048DFD5D5ED8FFFE0F37748" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_1481CD67DF9DFC7EF2358FFFE0F410DB" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/FairValueMeasurementTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/Goodwill" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/GoodwillAdjustmentsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_F6A2325735A342C3ECD08FFFE1C05F70" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_728A6E52CA153C513D538FFFE1BF70FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_F6A2325735A342C3ECD08FFFE1C05F70" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_728A6E52CA153C513D538FFFE1BF70FB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_F9A46C84B761EF5213468FFFE1BFDA25" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_728A6E52CA153C513D538FFFE1BF70FB" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_F9A46C84B761EF5213468FFFE1BFDA25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5C0A254DE5D6AF8449D58FFFE1BF014D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F9A46C84B761EF5213468FFFE1BFDA25" xlink:to="loc_us-gaap_SegmentDomain_5C0A254DE5D6AF8449D58FFFE1BF014D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5C0A254DE5D6AF8449D58FFFE1BF014D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F9A46C84B761EF5213468FFFE1BFDA25" xlink:to="loc_us-gaap_SegmentDomain_5C0A254DE5D6AF8449D58FFFE1BF014D" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_CAGMember" xlink:label="loc_lqdt_CAGMember_2DFA568A29027717D6C48FFFE1C022B9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5C0A254DE5D6AF8449D58FFFE1BF014D" xlink:to="loc_lqdt_CAGMember_2DFA568A29027717D6C48FFFE1C022B9" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_GovDealsMember" xlink:label="loc_lqdt_GovDealsMember_E938FE07F0845A8BDEE88FFFE1C0F7DF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5C0A254DE5D6AF8449D58FFFE1BF014D" xlink:to="loc_lqdt_GovDealsMember_E938FE07F0845A8BDEE88FFFE1C0F7DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_EC281098650806FFF4B78FFFE1C0748C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_F6A2325735A342C3ECD08FFFE1C05F70" xlink:to="loc_us-gaap_GoodwillRollForward_EC281098650806FFF4B78FFFE1C0748C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_988D9C86B7129BEF88C18FFFE1C1FEA9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_EC281098650806FFF4B78FFFE1C0748C" xlink:to="loc_us-gaap_Goodwill_988D9C86B7129BEF88C18FFFE1C1FEA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_E135A820CC3BB98B40888FFFE1C1224D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_EC281098650806FFF4B78FFFE1C0748C" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_E135A820CC3BB98B40888FFFE1C1224D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/GoodwillTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/Guarantees" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/GuaranteesNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxExaminationLineItems" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxExaminationTable" xlink:label="loc_us-gaap_IncomeTaxExaminationTable_2AF06E28C11714A07034B9895449B05A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:to="loc_us-gaap_IncomeTaxExaminationTable_2AF06E28C11714A07034B9895449B05A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_59C49B52480AD103086BB989544AAD27" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_2AF06E28C11714A07034B9895449B05A" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_59C49B52480AD103086BB989544AAD27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_CC75D2B39E9EEDC8CAA0B989544A8B93_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_59C49B52480AD103086BB989544AAD27" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_CC75D2B39E9EEDC8CAA0B989544A8B93_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_CC75D2B39E9EEDC8CAA0B989544A8B93" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_59C49B52480AD103086BB989544AAD27" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_CC75D2B39E9EEDC8CAA0B989544A8B93" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="loc_us-gaap_DomesticCountryMember_D794A6716D5B55F3D1C3B9895450B8D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_CC75D2B39E9EEDC8CAA0B989544A8B93" xlink:to="loc_us-gaap_DomesticCountryMember_D794A6716D5B55F3D1C3B9895450B8D0" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_TaxCutsandJobsActof2017BlendedTaxRatePercent" xlink:label="loc_lqdt_TaxCutsandJobsActof2017BlendedTaxRatePercent_93BEC5E528E327F76D3FB9895451CCC8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:to="loc_lqdt_TaxCutsandJobsActof2017BlendedTaxRatePercent_93BEC5E528E327F76D3FB9895451CCC8" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_TaxCutsandJobsActof2017ChangeinTaxRateDeferredTaxAssetIncomeTaxExpenseBenefit" xlink:label="loc_lqdt_TaxCutsandJobsActof2017ChangeinTaxRateDeferredTaxAssetIncomeTaxExpenseBenefit_44F6E75E055DE5E74D7CB98954516FC3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:to="loc_lqdt_TaxCutsandJobsActof2017ChangeinTaxRateDeferredTaxAssetIncomeTaxExpenseBenefit_44F6E75E055DE5E74D7CB98954516FC3" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_TaxCutsAndJobsActOf2017ChangeInTaxRateAlternativeMinimumIncomeTaxCreditIncomeTaxExpenseBenefit" xlink:label="loc_lqdt_TaxCutsAndJobsActOf2017ChangeInTaxRateAlternativeMinimumIncomeTaxCreditIncomeTaxExpenseBenefit_B34B4ABF9A8C31CB1527B9895452C88D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:to="loc_lqdt_TaxCutsAndJobsActOf2017ChangeInTaxRateAlternativeMinimumIncomeTaxCreditIncomeTaxExpenseBenefit_B34B4ABF9A8C31CB1527B9895452C88D" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_EstimatedEffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_lqdt_EstimatedEffectiveIncomeTaxRateContinuingOperations_C91EB0CABCDEA2701D0CB9895452A48A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:to="loc_lqdt_EstimatedEffectiveIncomeTaxRateContinuingOperations_C91EB0CABCDEA2701D0CB9895452A48A" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit" xlink:label="loc_lqdt_TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit_F0B6C5F064CFCE0E9B88B9895452155F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:to="loc_lqdt_TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit_F0B6C5F064CFCE0E9B88B9895452155F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxExaminationPenaltiesExpense" xlink:label="loc_us-gaap_IncomeTaxExaminationPenaltiesExpense_E95C800E57246EDA0FCBB9895452CE91" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_CFDADCAAAF398CDB6DD6B9895451AE75" xlink:to="loc_us-gaap_IncomeTaxExaminationPenaltiesExpense_E95C800E57246EDA0FCBB9895452CE91" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/IntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/IntangibleAssetsAmortizationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/IntangibleAssetsCarryingAmountDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_E333250932394F76572223120C8A12C5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4418B214D3D2265FE7FF23120C7AD38A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_E333250932394F76572223120C8A12C5" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4418B214D3D2265FE7FF23120C7AD38A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_53E55B73D894C0B4EA4323120C7A5B96" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4418B214D3D2265FE7FF23120C7AD38A" xlink:to="loc_us-gaap_RangeAxis_53E55B73D894C0B4EA4323120C7A5B96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_9F435E9CAE3DCB21E26C23120C7A7CC3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_53E55B73D894C0B4EA4323120C7A5B96" xlink:to="loc_us-gaap_RangeMember_9F435E9CAE3DCB21E26C23120C7A7CC3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_9F435E9CAE3DCB21E26C23120C7A7CC3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_53E55B73D894C0B4EA4323120C7A5B96" xlink:to="loc_us-gaap_RangeMember_9F435E9CAE3DCB21E26C23120C7A7CC3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_600F68DF2B117BD9F32D23120C7AFCB9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_9F435E9CAE3DCB21E26C23120C7A7CC3" xlink:to="loc_us-gaap_MinimumMember_600F68DF2B117BD9F32D23120C7AFCB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_B179FBBE7E965D0BDA9B23120C7A8227" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_9F435E9CAE3DCB21E26C23120C7A7CC3" xlink:to="loc_us-gaap_MaximumMember_B179FBBE7E965D0BDA9B23120C7A8227" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_FA2D1335B62E2567856123120C8A03F7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4418B214D3D2265FE7FF23120C7AD38A" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_FA2D1335B62E2567856123120C8A03F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38393C2F25E8D39C722E23120C8A6270_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_FA2D1335B62E2567856123120C8A03F7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38393C2F25E8D39C722E23120C8A6270_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38393C2F25E8D39C722E23120C8A6270" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_FA2D1335B62E2567856123120C8A03F7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38393C2F25E8D39C722E23120C8A6270" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_PatentsAndTrademarksMember" xlink:label="loc_lqdt_PatentsAndTrademarksMember_46964ADC3CCF8738AF1823120C8A35AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38393C2F25E8D39C722E23120C8A6270" xlink:to="loc_lqdt_PatentsAndTrademarksMember_46964ADC3CCF8738AF1823120C8A35AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_17F843779071D60465C023120C8A5781" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_E333250932394F76572223120C8A12C5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_17F843779071D60465C023120C8A5781" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_24AEA4BEAEA78EBD29DA23120C8AF459" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_E333250932394F76572223120C8A12C5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_24AEA4BEAEA78EBD29DA23120C8AF459" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_C9D96BF6A46E265EA71A23120C8A6DE5" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_E333250932394F76572223120C8A12C5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_C9D96BF6A46E265EA71A23120C8A6DE5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_C9190320ED881BCAF73423120C8A785E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_E333250932394F76572223120C8A12C5" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_C9190320ED881BCAF73423120C8A785E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/IntangibleAssetsNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/IntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/LegalProceedings" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/LegalProceedingsNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/Organization" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/OrganizationNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SegmentInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SegmentInformationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_6875B5CF541B1DDA6776DCF98D84F4BC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_AE64E2ED9488A0C6B1C6DCF98D6884D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_6875B5CF541B1DDA6776DCF98D84F4BC" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_AE64E2ED9488A0C6B1C6DCF98D6884D3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_B13C723076862DF3455FDCFA7845997C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_AE64E2ED9488A0C6B1C6DCF98D6884D3" xlink:to="loc_us-gaap_StatementGeographicalAxis_B13C723076862DF3455FDCFA7845997C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_9A15129BA1E268085288DCFA784B79B6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_B13C723076862DF3455FDCFA7845997C" xlink:to="loc_us-gaap_SegmentGeographicalDomain_9A15129BA1E268085288DCFA784B79B6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_9A15129BA1E268085288DCFA784B79B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_B13C723076862DF3455FDCFA7845997C" xlink:to="loc_us-gaap_SegmentGeographicalDomain_9A15129BA1E268085288DCFA784B79B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NonUsMember" xlink:label="loc_us-gaap_NonUsMember_8BC3A78F7888FC393F9FDCFB07A91508" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_9A15129BA1E268085288DCFA784B79B6" xlink:to="loc_us-gaap_NonUsMember_8BC3A78F7888FC393F9FDCFB07A91508" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_42B1453AB24B5F73BBDADCF98D69C052" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_AE64E2ED9488A0C6B1C6DCF98D6884D3" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_42B1453AB24B5F73BBDADCF98D69C052" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1404F22CAA4A034C512ADCF98D6F9404_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_42B1453AB24B5F73BBDADCF98D69C052" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1404F22CAA4A034C512ADCF98D6F9404_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1404F22CAA4A034C512ADCF98D6F9404" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_42B1453AB24B5F73BBDADCF98D69C052" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1404F22CAA4A034C512ADCF98D6F9404" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_D22EA6588041E1F5E39BDCFA5EE49B39" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1404F22CAA4A034C512ADCF98D6F9404" xlink:to="loc_us-gaap_SalesRevenueNetMember_D22EA6588041E1F5E39BDCFA5EE49B39" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_721DD0CD17706B25242ADCF98D7010C3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_AE64E2ED9488A0C6B1C6DCF98D6884D3" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_721DD0CD17706B25242ADCF98D7010C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_237466D4DB509F8893F2DCF98D705E45_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_721DD0CD17706B25242ADCF98D7010C3" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_237466D4DB509F8893F2DCF98D705E45_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_237466D4DB509F8893F2DCF98D705E45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_721DD0CD17706B25242ADCF98D7010C3" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_237466D4DB509F8893F2DCF98D705E45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GeographicConcentrationRiskMember" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_B7C94DE5D43F8634ED1BDCF9FECC1109" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_237466D4DB509F8893F2DCF98D705E45" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_B7C94DE5D43F8634ED1BDCF9FECC1109" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_762C2D8DC2798267B133DCF23ECB33D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_6875B5CF541B1DDA6776DCF98D84F4BC" xlink:to="loc_us-gaap_NumberOfReportableSegments_762C2D8DC2798267B133DCF23ECB33D8" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ReportableSegmentsPercentageofRevenue" xlink:label="loc_lqdt_ReportableSegmentsPercentageofRevenue_F142071D48AAD042D6C1DCF23ECB5573" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_6875B5CF541B1DDA6776DCF98D84F4BC" xlink:to="loc_lqdt_ReportableSegmentsPercentageofRevenue_F142071D48AAD042D6C1DCF23ECB5573" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_DEF911901C9BCA56824EDCF8DA8BE44E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_6875B5CF541B1DDA6776DCF98D84F4BC" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_DEF911901C9BCA56824EDCF8DA8BE44E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SegmentInformationReconciliationOfRevenueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E8D7240F62E9BC350F18B989E8A24DE6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E8D7240F62E9BC350F18B989E8A24DE6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_0ED22FD24CC96F2EA60BB989E8A27C1A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E8D7240F62E9BC350F18B989E8A24DE6" xlink:to="loc_us-gaap_ConsolidationItemsAxis_0ED22FD24CC96F2EA60BB989E8A27C1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_D70DE4479E745230D418B989E8A3B890_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_0ED22FD24CC96F2EA60BB989E8A27C1A" xlink:to="loc_us-gaap_ConsolidationItemsDomain_D70DE4479E745230D418B989E8A3B890_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_D70DE4479E745230D418B989E8A3B890" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_0ED22FD24CC96F2EA60BB989E8A27C1A" xlink:to="loc_us-gaap_ConsolidationItemsDomain_D70DE4479E745230D418B989E8A3B890" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_628CD94ABB3F43358157B989E8A35677" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_D70DE4479E745230D418B989E8A3B890" xlink:to="loc_us-gaap_OperatingSegmentsMember_628CD94ABB3F43358157B989E8A35677" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_752525864D392C280094B989E8A4CC54" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_D70DE4479E745230D418B989E8A3B890" xlink:to="loc_us-gaap_CorporateNonSegmentMember_752525864D392C280094B989E8A4CC54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_AAE45541159BE5D72FA5B989E8A49671" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E8D7240F62E9BC350F18B989E8A24DE6" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_AAE45541159BE5D72FA5B989E8A49671" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_56D7BD151744630D65CFB989E8A4F754_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AAE45541159BE5D72FA5B989E8A49671" xlink:to="loc_us-gaap_SegmentDomain_56D7BD151744630D65CFB989E8A4F754_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_56D7BD151744630D65CFB989E8A4F754" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AAE45541159BE5D72FA5B989E8A49671" xlink:to="loc_us-gaap_SegmentDomain_56D7BD151744630D65CFB989E8A4F754" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_GovDealsMember" xlink:label="loc_lqdt_GovDealsMember_1C78FB4D426DAAF11089B989E8A4D738" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_56D7BD151744630D65CFB989E8A4F754" xlink:to="loc_lqdt_GovDealsMember_1C78FB4D426DAAF11089B989E8A4D738" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_CAGMember" xlink:label="loc_lqdt_CAGMember_3C93D9F9B4ADAD2B1016B989E8A4B1AF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_56D7BD151744630D65CFB989E8A4F754" xlink:to="loc_lqdt_CAGMember_3C93D9F9B4ADAD2B1016B989E8A4B1AF" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_RSCGMember" xlink:label="loc_lqdt_RSCGMember_64252392171DA989BEF7B989E8A53F05" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_56D7BD151744630D65CFB989E8A4F754" xlink:to="loc_lqdt_RSCGMember_64252392171DA989BEF7B989E8A53F05" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_2FA18436D47153B47BA6B989E8A5366A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:to="loc_us-gaap_SalesRevenueNet_2FA18436D47153B47BA6B989E8A5366A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_E277601C5226394F7847B989E8A7DF1F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:to="loc_us-gaap_GrossProfit_E277601C5226394F7847B989E8A7DF1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_DB66DA1A0B36FD075024B989E8A7ECCB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:to="loc_us-gaap_OperatingExpenses_DB66DA1A0B36FD075024B989E8A7ECCB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_InterestIncomeExpenseNet" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_03079FB7B6486E1014D1B989E8A82A3B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_03079FB7B6486E1014D1B989E8A82A3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_3E300FB0DC94B13E8E0AB989E8A8A227" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_3E300FB0DC94B13E8E0AB989E8A8A227" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_E471B5DC66FCF5138CECB989E8A89D67" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_2C69386055C072CBCE3CB989E8A50A82" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_E471B5DC66FCF5138CECB989E8A89D67" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SegmentInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SignificantContracts" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SignificantContractsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_CC9EF0B01200064B517EB989E96986BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_CC9EF0B01200064B517EB989E96986BC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProductOrServiceAxis" xlink:label="loc_us-gaap_ProductOrServiceAxis_266EC7422965AF6C3990B989E9699D8A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_CC9EF0B01200064B517EB989E96986BC" xlink:to="loc_us-gaap_ProductOrServiceAxis_266EC7422965AF6C3990B989E9699D8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_4865D4C7F09B2E7C97E1B989E9692250_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ProductOrServiceAxis_266EC7422965AF6C3990B989E9699D8A" xlink:to="loc_us-gaap_ProductsAndServicesDomain_4865D4C7F09B2E7C97E1B989E9692250_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProductsAndServicesDomain" xlink:label="loc_us-gaap_ProductsAndServicesDomain_4865D4C7F09B2E7C97E1B989E9692250" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ProductOrServiceAxis_266EC7422965AF6C3990B989E9699D8A" xlink:to="loc_us-gaap_ProductsAndServicesDomain_4865D4C7F09B2E7C97E1B989E9692250" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_NonrollingStockSurplusContractMember" xlink:label="loc_lqdt_NonrollingStockSurplusContractMember_83001403542296A371F7B989E96ACB5B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductsAndServicesDomain_4865D4C7F09B2E7C97E1B989E9692250" xlink:to="loc_lqdt_NonrollingStockSurplusContractMember_83001403542296A371F7B989E96ACB5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaap_TypeOfArrangementAxis_F401B1B40EC2EAD9650DB989E96F23D3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_CC9EF0B01200064B517EB989E96986BC" xlink:to="loc_us-gaap_TypeOfArrangementAxis_F401B1B40EC2EAD9650DB989E96F23D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_7A6D0CCADE60EF143149B989E96F475A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_F401B1B40EC2EAD9650DB989E96F23D3" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_7A6D0CCADE60EF143149B989E96F475A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_7A6D0CCADE60EF143149B989E96F475A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_F401B1B40EC2EAD9650DB989E96F23D3" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_7A6D0CCADE60EF143149B989E96F475A" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_SurplusContractMember" xlink:label="loc_lqdt_SurplusContractMember_712A48AE7DCAD07B0C8DB989E9702273" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_7A6D0CCADE60EF143149B989E96F475A" xlink:to="loc_lqdt_SurplusContractMember_712A48AE7DCAD07B0C8DB989E9702273" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ScrapContractMember" xlink:label="loc_lqdt_ScrapContractMember_CA18078A0E8DDF753EB0B989E970B4AA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_7A6D0CCADE60EF143149B989E96F475A" xlink:to="loc_lqdt_ScrapContractMember_CA18078A0E8DDF753EB0B989E970B4AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_9EBAB65A418196CFC7FAB989E9707D24" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_CC9EF0B01200064B517EB989E96986BC" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_9EBAB65A418196CFC7FAB989E9707D24" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_0CBA012E120CAF642E4DB989E970E968_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_9EBAB65A418196CFC7FAB989E9707D24" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_0CBA012E120CAF642E4DB989E970E968_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_0CBA012E120CAF642E4DB989E970E968" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_9EBAB65A418196CFC7FAB989E9707D24" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_0CBA012E120CAF642E4DB989E970E968" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_8667C9332CA7DED0F9E6B989E971C1ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_0CBA012E120CAF642E4DB989E970E968" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_8667C9332CA7DED0F9E6B989E971C1ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_632A6416ED6853C083C0B989E971E39A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_CC9EF0B01200064B517EB989E96986BC" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_632A6416ED6853C083C0B989E971E39A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_34E989A0A92A6CDD6DA6B989E9716EB9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_632A6416ED6853C083C0B989E971E39A" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_34E989A0A92A6CDD6DA6B989E9716EB9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_34E989A0A92A6CDD6DA6B989E9716EB9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_632A6416ED6853C083C0B989E971E39A" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_34E989A0A92A6CDD6DA6B989E9716EB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_E19477AE19747CF94F49B989E971CA9F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_34E989A0A92A6CDD6DA6B989E9716EB9" xlink:to="loc_us-gaap_SalesRevenueNetMember_E19477AE19747CF94F49B989E971CA9F" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_NumberOfContracts" xlink:label="loc_lqdt_NumberOfContracts_DA6B308452C13D102173B993E5B981E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_NumberOfContracts_DA6B308452C13D102173B993E5B981E5" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ContractTerm" xlink:label="loc_lqdt_ContractTerm_9FA5FDE0B430E05CEB66B989E97272F9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_ContractTerm_9FA5FDE0B430E05CEB66B989E97272F9" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_RevenueFromContractWithCustomerNumberOfContractExtensions" xlink:label="loc_lqdt_RevenueFromContractWithCustomerNumberOfContractExtensions_472CDD359D6A182A589DB989E9723B96" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_RevenueFromContractWithCustomerNumberOfContractExtensions_472CDD359D6A182A589DB989E9723B96" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_RenewalOptionsExtendedTerm" xlink:label="loc_lqdt_RenewalOptionsExtendedTerm_9A664FCAC028B1062A00B989E9722E8B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_RenewalOptionsExtendedTerm_9A664FCAC028B1062A00B989E9722E8B" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_AdjustedPercentageOfProfitSharingDistribution" xlink:label="loc_lqdt_AdjustedPercentageOfProfitSharingDistribution_13951452F1E3735E532BB989E972D582" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_AdjustedPercentageOfProfitSharingDistribution_13951452F1E3735E532BB989E972D582" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_3EBBC6008AF2571D5066B989E9736403" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_3EBBC6008AF2571D5066B989E9736403" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_UsableSurplusPropertyToBePurchasedAsPercentageOfOriginalAcquisitionValue" xlink:label="loc_lqdt_UsableSurplusPropertyToBePurchasedAsPercentageOfOriginalAcquisitionValue_ED7C81C495D1D59646E2B989E973DB18" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_UsableSurplusPropertyToBePurchasedAsPercentageOfOriginalAcquisitionValue_ED7C81C495D1D59646E2B989E973DB18" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_PercentageOfProfitsRetained" xlink:label="loc_lqdt_PercentageOfProfitsRetained_691A4F8536EA0D51DFBEB989E973BC2B" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_PercentageOfProfitsRetained_691A4F8536EA0D51DFBEB989E973BC2B" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_AccruedExpensesAndOtherCurrentLiabilities" xlink:label="loc_lqdt_AccruedExpensesAndOtherCurrentLiabilities_2B6448DF43CCB442AA10B989E973F683" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_8A636EDF6E62A31CA910B989E972EF3F" xlink:to="loc_lqdt_AccruedExpensesAndOtherCurrentLiabilities_2B6448DF43CCB442AA10B989E973F683" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/StockholdersEquity" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/StockholdersEquity2006PlanActivityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13E83D7392536F5AEBFD23120DC9CE0A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_44A2884D21214160060B23120DC950D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13E83D7392536F5AEBFD23120DC9CE0A" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_44A2884D21214160060B23120DC950D0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_4B10EDB9C504113D1AF023120DC9A05C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_44A2884D21214160060B23120DC950D0" xlink:to="loc_us-gaap_AwardTypeAxis_4B10EDB9C504113D1AF023120DC9A05C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88BEC2A3E5448F876CF023120DC938BB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4B10EDB9C504113D1AF023120DC9A05C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88BEC2A3E5448F876CF023120DC938BB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88BEC2A3E5448F876CF023120DC938BB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4B10EDB9C504113D1AF023120DC9A05C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88BEC2A3E5448F876CF023120DC938BB" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_EmployeeAndNonEmployeesStockOptionMember" xlink:label="loc_lqdt_EmployeeAndNonEmployeesStockOptionMember_79A0E84A2A9EC463559A23120DC9FCAD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88BEC2A3E5448F876CF023120DC938BB" xlink:to="loc_lqdt_EmployeeAndNonEmployeesStockOptionMember_79A0E84A2A9EC463559A23120DC9FCAD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_53032BC35EBF271308DA23120DC955AC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13E83D7392536F5AEBFD23120DC9CE0A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_53032BC35EBF271308DA23120DC955AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_665A0038067395E1081423120DC9BAFF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_53032BC35EBF271308DA23120DC955AC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_665A0038067395E1081423120DC9BAFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_E05ED77E4E166C1AFD1B23120DC9AD87" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_53032BC35EBF271308DA23120DC955AC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_E05ED77E4E166C1AFD1B23120DC9AD87" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_4791DF1A1AE1F3B65A8023120DC9176B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_53032BC35EBF271308DA23120DC955AC" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_4791DF1A1AE1F3B65A8023120DC9176B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_FC398C398FE9D3BF9F0523120DC9C093" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_53032BC35EBF271308DA23120DC955AC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_FC398C398FE9D3BF9F0523120DC9C093" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_BADDCBD95EEA7B203BC223120DC91661" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_53032BC35EBF271308DA23120DC955AC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_BADDCBD95EEA7B203BC223120DC91661" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_E403FB93BAF79D78A4ED23120DC9263C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13E83D7392536F5AEBFD23120DC9CE0A" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_E403FB93BAF79D78A4ED23120DC9263C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_737F67E86CC927A8A1D123120DC976C8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_E403FB93BAF79D78A4ED23120DC9263C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_737F67E86CC927A8A1D123120DC976C8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_ADED4E46A520DE9EE5D223120DC915A5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_E403FB93BAF79D78A4ED23120DC9263C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_ADED4E46A520DE9EE5D223120DC915A5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_5792FC396E863F9E82BA23120DC9FDDD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_E403FB93BAF79D78A4ED23120DC9263C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_5792FC396E863F9E82BA23120DC9FDDD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_3D335A983C0F0E70EE2323120DC97E70" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_E403FB93BAF79D78A4ED23120DC9263C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_3D335A983C0F0E70EE2323120DC97E70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_E5D1A597A75CA2F57D5223120DC97331" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_E403FB93BAF79D78A4ED23120DC9263C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_E5D1A597A75CA2F57D5223120DC97331" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/StockholdersEquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E6595F1ACE6ABAE074E3E3639155642A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E6595F1ACE6ABAE074E3E3639155642A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_F0A611B13525A913B8E6E36391559732" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E6595F1ACE6ABAE074E3E3639155642A" xlink:to="loc_us-gaap_AwardTypeAxis_F0A611B13525A913B8E6E36391559732" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_F0A611B13525A913B8E6E36391559732" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_F0A611B13525A913B8E6E36391559732" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_StockOptionsOrStockAppreciationRightsMember" xlink:label="loc_lqdt_StockOptionsOrStockAppreciationRightsMember_24A295F610C68FB3C7F0E3639155336A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C" xlink:to="loc_lqdt_StockOptionsOrStockAppreciationRightsMember_24A295F610C68FB3C7F0E3639155336A" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_OtherThanStockOptionsOrStockAppreciationRightsMember" xlink:label="loc_lqdt_OtherThanStockOptionsOrStockAppreciationRightsMember_0709264DA307E38D3164E3639155E056" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C" xlink:to="loc_lqdt_OtherThanStockOptionsOrStockAppreciationRightsMember_0709264DA307E38D3164E3639155E056" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_EmployeeAndNonEmployeesStockOptionMember" xlink:label="loc_lqdt_EmployeeAndNonEmployeesStockOptionMember_790F8B41E88C48E66428E36391556165" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C" xlink:to="loc_lqdt_EmployeeAndNonEmployeesStockOptionMember_790F8B41E88C48E66428E36391556165" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockAppreciationRightsSARSMember" xlink:label="loc_us-gaap_StockAppreciationRightsSARSMember_8637BE80327AA6AAEBF2E363915506B9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C" xlink:to="loc_us-gaap_StockAppreciationRightsSARSMember_8637BE80327AA6AAEBF2E363915506B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_D2A52ED8D3BAC48153F5E3639155ABEA" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2372D6CBFE4264AB2F12E3639155091C" xlink:to="loc_us-gaap_RestrictedStockMember_D2A52ED8D3BAC48153F5E3639155ABEA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_1E2CECD66EE5C00E0512E363915844D1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_E6595F1ACE6ABAE074E3E3639155642A" xlink:to="loc_us-gaap_RangeAxis_1E2CECD66EE5C00E0512E363915844D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_D3DD33094D383A913C78E36391582207_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_1E2CECD66EE5C00E0512E363915844D1" xlink:to="loc_us-gaap_RangeMember_D3DD33094D383A913C78E36391582207_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_D3DD33094D383A913C78E36391582207" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_1E2CECD66EE5C00E0512E363915844D1" xlink:to="loc_us-gaap_RangeMember_D3DD33094D383A913C78E36391582207" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_8DF52588AABCEE2788E0E36391588169" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_D3DD33094D383A913C78E36391582207" xlink:to="loc_us-gaap_MinimumMember_8DF52588AABCEE2788E0E36391588169" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_16D832A5EC66A4571366E36391588F71" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_D3DD33094D383A913C78E36391582207" xlink:to="loc_us-gaap_MaximumMember_16D832A5EC66A4571366E36391588F71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_40E555DFB4B9C2CF0113E3639158FE0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_40E555DFB4B9C2CF0113E3639158FE0A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_81775EF55850AED319ADE36391589FCC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_81775EF55850AED319ADE36391589FCC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_4DFF6004CB116AE113A6E36391583C53" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_4DFF6004CB116AE113A6E36391583C53" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_NumberOfSharesCountedForGrantsOfFullValueAwardsFromReserve" xlink:label="loc_lqdt_NumberOfSharesCountedForGrantsOfFullValueAwardsFromReserve_AB1B466609856AF50F1EE36391587C65" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_lqdt_NumberOfSharesCountedForGrantsOfFullValueAwardsFromReserve_AB1B466609856AF50F1EE36391587C65" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAwardedPerPersonPerYear" xlink:label="loc_lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAwardedPerPersonPerYear_310EB41DBB5C6D37CE51E3639158B5FD" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAwardedPerPersonPerYear_310EB41DBB5C6D37CE51E3639158B5FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_F9C1D7C87CCE2DEBB3DEE36391582736" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_F9C1D7C87CCE2DEBB3DEE36391582736" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_BC11A6BA1A3CD00C5268E36499D63A55" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_BC11A6BA1A3CD00C5268E36499D63A55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5347B621B6AE2254996EE3639158113F" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5347B621B6AE2254996EE3639158113F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_380BCAD8F9484C7B5BA5E365503FE259" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_380BCAD8F9484C7B5BA5E365503FE259" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_18A06C582417B5B17223E363915AF605" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_18A06C582417B5B17223E363915AF605" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_61D53194020883540111E363915AF62F" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_61D53194020883540111E363915AF62F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_5935909F889A3968135EE363915A5F2E" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_5935909F889A3968135EE363915A5F2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_D7687303D5406DC12B54E363915AA955" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_D7687303D5406DC12B54E363915AA955" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_CF555C98227880EBC959E363915AA156" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_CF555C98227880EBC959E363915AA156" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_A96ADD7861F7DA432460E363915AE335" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_A96ADD7861F7DA432460E363915AE335" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaap_SharePrice_17723315C763E2A053C2E363915A6668" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_SharePrice_17723315C763E2A053C2E363915A6668" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_EBFE645D25FC72390173E363915A6620" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_EBFE645D25FC72390173E363915A6620" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_057415288EA18A16A175E363915A8359" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_057415288EA18A16A175E363915A8359" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_0E46541B8667175697B9E363915A3E69" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_0E46541B8667175697B9E363915A3E69" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_A5057EE96FDE7876412FE363915AA4C1" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_A5057EE96FDE7876412FE363915AA4C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_138DE118AB5084119672E363915ADAE6" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_138DE118AB5084119672E363915ADAE6" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate" xlink:label="loc_lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate_BBD45A05195A90B613D2E363915AFA24" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate_BBD45A05195A90B613D2E363915AFA24" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedTotalIntrinsicValue" xlink:label="loc_lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedTotalIntrinsicValue_45F9C1547641062CD298E363915AD89D" xlink:type="locator" />
    <link:definitionArc order="23" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_lqdt_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedTotalIntrinsicValue_45F9C1547641062CD298E363915AD89D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_0A260FF8F5CB85FD15F2E363915DA0A4" xlink:type="locator" />
    <link:definitionArc order="24" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61357B94F28C5C215507E3639158B208" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_0A260FF8F5CB85FD15F2E363915DA0A4" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/StockholdersEquityRestrictedShareActivityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1C4F87CD8455D6C675E523120C6B82A7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C700747E8B4251A4A83923120C5BC5A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1C4F87CD8455D6C675E523120C6B82A7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C700747E8B4251A4A83923120C5BC5A9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_7350870C4187A535F3D123120C5B852C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_C700747E8B4251A4A83923120C5BC5A9" xlink:to="loc_us-gaap_AwardTypeAxis_7350870C4187A535F3D123120C5B852C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24EE8EDE8B69C3FD1B0323120C5B24B4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_7350870C4187A535F3D123120C5B852C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24EE8EDE8B69C3FD1B0323120C5B24B4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24EE8EDE8B69C3FD1B0323120C5B24B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_7350870C4187A535F3D123120C5B852C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24EE8EDE8B69C3FD1B0323120C5B24B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_50478438C08357BF3D3F23120C5B601F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_24EE8EDE8B69C3FD1B0323120C5B24B4" xlink:to="loc_us-gaap_RestrictedStockMember_50478438C08357BF3D3F23120C5B601F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D334BC34A70F2E56D52323120C6B3546" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1C4F87CD8455D6C675E523120C6B82A7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D334BC34A70F2E56D52323120C6B3546" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6B17886B2105BD2D28ED23120C6B040C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D334BC34A70F2E56D52323120C6B3546" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6B17886B2105BD2D28ED23120C6B040C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_643B0103A3C30D07448F23120C6BF66D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D334BC34A70F2E56D52323120C6B3546" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_643B0103A3C30D07448F23120C6BF66D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_69BAEEE3E0FF261CEA3423120C6B9C83" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D334BC34A70F2E56D52323120C6B3546" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_69BAEEE3E0FF261CEA3423120C6B9C83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_B663C161F83FC5331B0D23120C6B603B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_D334BC34A70F2E56D52323120C6B3546" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_B663C161F83FC5331B0D23120C6B603B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_B62A3C85CD5E2786272423120C6B9CFF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1C4F87CD8455D6C675E523120C6B82A7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_B62A3C85CD5E2786272423120C6B9CFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_67C77B01E46C43D75EC223120C6BF7F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_B62A3C85CD5E2786272423120C6B9CFF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_67C77B01E46C43D75EC223120C6BF7F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2194D6ACEE85EB4EB2F623120C6B1BD7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_B62A3C85CD5E2786272423120C6B9CFF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_2194D6ACEE85EB4EB2F623120C6B1BD7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_7889E9D3087A654DFF4523120C6B5E5E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_B62A3C85CD5E2786272423120C6B9CFF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_7889E9D3087A654DFF4523120C6B5E5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_8C4D4F1F2DD0F8FA487523120C6BC04F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_B62A3C85CD5E2786272423120C6B9CFF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_8C4D4F1F2DD0F8FA487523120C6BC04F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/StockholdersEquityTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SubsequentEvent" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SubsequentEventNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_427ED87A03AC1C1750B7D6A2ACE132B6" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_7CC60DB2A393EFEDA4CAD6A2ACDFB5A5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_427ED87A03AC1C1750B7D6A2ACE132B6" xlink:to="loc_us-gaap_SubsequentEventTable_7CC60DB2A393EFEDA4CAD6A2ACDFB5A5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_814A0DC24B084D4FC569D6A2ACDFD1D1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_7CC60DB2A393EFEDA4CAD6A2ACDFB5A5" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_814A0DC24B084D4FC569D6A2ACDFD1D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_91E3AA9932C5755D5282D6A2ACE02F9E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_814A0DC24B084D4FC569D6A2ACDFD1D1" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_91E3AA9932C5755D5282D6A2ACE02F9E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_91E3AA9932C5755D5282D6A2ACE02F9E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_814A0DC24B084D4FC569D6A2ACDFD1D1" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_91E3AA9932C5755D5282D6A2ACE02F9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_A3223F608482294519AFD6A2ACE0006F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_91E3AA9932C5755D5282D6A2ACE02F9E" xlink:to="loc_us-gaap_SubsequentEventMember_A3223F608482294519AFD6A2ACE0006F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_91E9EC5FE6C23D57AB44D6B6DAADA084" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_7CC60DB2A393EFEDA4CAD6A2ACDFB5A5" xlink:to="loc_us-gaap_RangeAxis_91E9EC5FE6C23D57AB44D6B6DAADA084" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_14A80D1019E21A77AD73D6B6DAC4AF62_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_91E9EC5FE6C23D57AB44D6B6DAADA084" xlink:to="loc_us-gaap_RangeMember_14A80D1019E21A77AD73D6B6DAC4AF62_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_14A80D1019E21A77AD73D6B6DAC4AF62" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_91E9EC5FE6C23D57AB44D6B6DAADA084" xlink:to="loc_us-gaap_RangeMember_14A80D1019E21A77AD73D6B6DAC4AF62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_D67A2ACD4A2EC0C119E0D6B6FA0EFC3C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_14A80D1019E21A77AD73D6B6DAC4AF62" xlink:to="loc_us-gaap_MaximumMember_D67A2ACD4A2EC0C119E0D6B6FA0EFC3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_C14A8C44CA4AD868641CD6A2ACE1EE0C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_427ED87A03AC1C1750B7D6A2ACE132B6" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_C14A8C44CA4AD868641CD6A2ACE1EE0C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_CD3197DB3FABAD227335D6A2ACE126B4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_427ED87A03AC1C1750B7D6A2ACE132B6" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_CD3197DB3FABAD227335D6A2ACE126B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_FB6DE27A0D31426CABB1D6ABD526E82D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_427ED87A03AC1C1750B7D6A2ACE132B6" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_FB6DE27A0D31426CABB1D6ABD526E82D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesEarningsPerShareDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_23E6BE1736C8D5E8E67DB989E9B060AE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_23E6BE1736C8D5E8E67DB989E9B060AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_E8BA9671AE046DCC8449B989E9B09837_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_23E6BE1736C8D5E8E67DB989E9B060AE" xlink:to="loc_us-gaap_TypeOfAdoptionMember_E8BA9671AE046DCC8449B989E9B09837_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_E8BA9671AE046DCC8449B989E9B09837" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_23E6BE1736C8D5E8E67DB989E9B060AE" xlink:to="loc_us-gaap_TypeOfAdoptionMember_E8BA9671AE046DCC8449B989E9B09837" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccountingStandardsUpdate201609Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201609Member_1AA6BDBEF66C58C0C48EB989E9B088A5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_E8BA9671AE046DCC8449B989E9B09837" xlink:to="loc_us-gaap_AccountingStandardsUpdate201609Member_1AA6BDBEF66C58C0C48EB989E9B088A5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_C5C05D94312909BA8588B989E9B1407B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_C5C05D94312909BA8588B989E9B1407B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_32A9980A731405534C40B989E9B15D61_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_C5C05D94312909BA8588B989E9B1407B" xlink:to="loc_us-gaap_EquityComponentDomain_32A9980A731405534C40B989E9B15D61_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_32A9980A731405534C40B989E9B15D61" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_C5C05D94312909BA8588B989E9B1407B" xlink:to="loc_us-gaap_EquityComponentDomain_32A9980A731405534C40B989E9B15D61" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_2FDE2012B85F1A09F9DEB989E9B1D406" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_32A9980A731405534C40B989E9B15D61" xlink:to="loc_us-gaap_RetainedEarningsMember_2FDE2012B85F1A09F9DEB989E9B1D406" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfReceivablesWithImputedInterestNameOfReceivableWithImputedInterestAxis" xlink:label="loc_us-gaap_ScheduleOfReceivablesWithImputedInterestNameOfReceivableWithImputedInterestAxis_B8A14DB896871DC8A721B989E9B297DE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:to="loc_us-gaap_ScheduleOfReceivablesWithImputedInterestNameOfReceivableWithImputedInterestAxis_B8A14DB896871DC8A721B989E9B297DE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NameOfReceivableWithImputedInterestDomain" xlink:label="loc_us-gaap_NameOfReceivableWithImputedInterestDomain_E8A61C7312B00AB1D296B989E9B2D28D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ScheduleOfReceivablesWithImputedInterestNameOfReceivableWithImputedInterestAxis_B8A14DB896871DC8A721B989E9B297DE" xlink:to="loc_us-gaap_NameOfReceivableWithImputedInterestDomain_E8A61C7312B00AB1D296B989E9B2D28D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NameOfReceivableWithImputedInterestDomain" xlink:label="loc_us-gaap_NameOfReceivableWithImputedInterestDomain_E8A61C7312B00AB1D296B989E9B2D28D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ScheduleOfReceivablesWithImputedInterestNameOfReceivableWithImputedInterestAxis_B8A14DB896871DC8A721B989E9B297DE" xlink:to="loc_us-gaap_NameOfReceivableWithImputedInterestDomain_E8A61C7312B00AB1D296B989E9B2D28D" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_TanagerAcquisitionsPromissoryNoteMember" xlink:label="loc_lqdt_TanagerAcquisitionsPromissoryNoteMember_95E9FBF1258331686491B989E9B2035D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfReceivableWithImputedInterestDomain_E8A61C7312B00AB1D296B989E9B2D28D" xlink:to="loc_lqdt_TanagerAcquisitionsPromissoryNoteMember_95E9FBF1258331686491B989E9B2035D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_E40E9E19F5B12D7779DDB989E9B23371" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_E40E9E19F5B12D7779DDB989E9B23371" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_352B56BF3D8CDD811BBCB989E9B3D071_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_E40E9E19F5B12D7779DDB989E9B23371" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_352B56BF3D8CDD811BBCB989E9B3D071_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_352B56BF3D8CDD811BBCB989E9B3D071" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_E40E9E19F5B12D7779DDB989E9B23371" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_352B56BF3D8CDD811BBCB989E9B3D071" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherAssetsMember" xlink:label="loc_us-gaap_OtherAssetsMember_C8D86A120D65C598B43CB989E9B312C1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_352B56BF3D8CDD811BBCB989E9B3D071" xlink:to="loc_us-gaap_OtherAssetsMember_C8D86A120D65C598B43CB989E9B312C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:label="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_D1576FF95C82DC7E643DB989E9B307F9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_352B56BF3D8CDD811BBCB989E9B3D071" xlink:to="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_D1576FF95C82DC7E643DB989E9B307F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_1EAE77232B21A41EFEC4B989E9B3DAB2" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_1EAE77232B21A41EFEC4B989E9B3DAB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_AB83349D56FDF7C3E94EB989E9B30009_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_1EAE77232B21A41EFEC4B989E9B3DAB2" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_AB83349D56FDF7C3E94EB989E9B30009_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_AB83349D56FDF7C3E94EB989E9B30009" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_1EAE77232B21A41EFEC4B989E9B3DAB2" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_AB83349D56FDF7C3E94EB989E9B30009" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_EF17C30D78F2969B9C4EB989E9B4950E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_AB83349D56FDF7C3E94EB989E9B30009" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_EF17C30D78F2969B9C4EB989E9B4950E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SupplierConcentrationRiskMember" xlink:label="loc_us-gaap_SupplierConcentrationRiskMember_BC79666A13BE7963377DB989E9B45EB2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_AB83349D56FDF7C3E94EB989E9B30009" xlink:to="loc_us-gaap_SupplierConcentrationRiskMember_BC79666A13BE7963377DB989E9B45EB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_AD7B89C6031C8069120FB989E9B96861" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_AD7B89C6031C8069120FB989E9B96861" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_E2853F49346C48625971B989E9BAB485_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_AD7B89C6031C8069120FB989E9B96861" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_E2853F49346C48625971B989E9BAB485_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_E2853F49346C48625971B989E9BAB485" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_AD7B89C6031C8069120FB989E9B96861" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_E2853F49346C48625971B989E9BAB485" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_68C09E182E26F7266C69B989E9BAD77C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_E2853F49346C48625971B989E9BAB485" xlink:to="loc_us-gaap_SalesRevenueNetMember_68C09E182E26F7266C69B989E9BAD77C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostOfGoodsTotalMember" xlink:label="loc_us-gaap_CostOfGoodsTotalMember_72B6A9A1844A8CD642D5B989E9BAB4F6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_E2853F49346C48625971B989E9BAB485" xlink:to="loc_us-gaap_CostOfGoodsTotalMember_72B6A9A1844A8CD642D5B989E9BAB4F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaap_TypeOfArrangementAxis_9ADEA18E088A157F1AEEB989E9BA30C7" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_6F74DE756420BDF027D3B989E9AF0F5C" xlink:to="loc_us-gaap_TypeOfArrangementAxis_9ADEA18E088A157F1AEEB989E9BA30C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_00CB99FBEF8246896FFCB989E9BB0ADB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_9ADEA18E088A157F1AEEB989E9BA30C7" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_00CB99FBEF8246896FFCB989E9BB0ADB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_00CB99FBEF8246896FFCB989E9BB0ADB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_9ADEA18E088A157F1AEEB989E9BA30C7" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_00CB99FBEF8246896FFCB989E9BB0ADB" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_SurplusContractMember" xlink:label="loc_lqdt_SurplusContractMember_7A9BF63F88B5A5B09A87B989E9BB548B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_00CB99FBEF8246896FFCB989E9BB0ADB" xlink:to="loc_lqdt_SurplusContractMember_7A9BF63F88B5A5B09A87B989E9BB548B" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ScrapContractMember" xlink:label="loc_lqdt_ScrapContractMember_B8B0CD08812B3EED70C3B989E9BB047E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_00CB99FBEF8246896FFCB989E9BB0ADB" xlink:to="loc_lqdt_ScrapContractMember_B8B0CD08812B3EED70C3B989E9BB047E" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ContractWithCommercialClientMember" xlink:label="loc_lqdt_ContractWithCommercialClientMember_2F0FD7CBABFFE886BA67B989E9BB894F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_00CB99FBEF8246896FFCB989E9BB0ADB" xlink:to="loc_lqdt_ContractWithCommercialClientMember_2F0FD7CBABFFE886BA67B989E9BB894F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption" xlink:label="loc_us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_7A31C075117ADAB187CAB989E9BC72FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption_7A31C075117ADAB187CAB989E9BC72FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ReceivableWithImputedInterestFaceAmount" xlink:label="loc_us-gaap_ReceivableWithImputedInterestFaceAmount_08EF37AB4966D7F9A854B989E9BCDD8E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_us-gaap_ReceivableWithImputedInterestFaceAmount_08EF37AB4966D7F9A854B989E9BCDD8E" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_ReceivableWithImputedInterestTerm" xlink:label="loc_lqdt_ReceivableWithImputedInterestTerm_1AD405A6B82C7E3C414EB989E9BC9146" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_lqdt_ReceivableWithImputedInterestTerm_1AD405A6B82C7E3C414EB989E9BC9146" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ProceedsFromCollectionOfNotesReceivable" xlink:label="loc_us-gaap_ProceedsFromCollectionOfNotesReceivable_202E7E7A3A3A7E94E9F9B989E9BCCDD8" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_us-gaap_ProceedsFromCollectionOfNotesReceivable_202E7E7A3A3A7E94E9F9B989E9BCCDD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ReceivableWithImputedInterestNetAmount" xlink:label="loc_us-gaap_ReceivableWithImputedInterestNetAmount_1271C0F7B520527376FDB989E9BD8A22" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_us-gaap_ReceivableWithImputedInterestNetAmount_1271C0F7B520527376FDB989E9BD8A22" xlink:type="arc" />
    <link:loc xlink:href="lqdt-20180630.xsd#lqdt_NumberOfContracts" xlink:label="loc_lqdt_NumberOfContracts_3D64C6FB85319416FA0EB9934683A8E9" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_lqdt_NumberOfContracts_3D64C6FB85319416FA0EB9934683A8E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_1099F4E43407E66785E0B989E9BD9963" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_A8AD2F83FF6D9440D942B989E9BC0B0C" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_1099F4E43407E66785E0B989E9BD9963" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/UnauditedConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/UnauditedConsolidatedStatementsOfComprehensiveLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liquidityservices.com/role/UnauditedConsolidatedStatementsOfOperations" xlink:type="extended" />
</link:linkbase>
