<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e5049-3167-72f3-9515-63cbb66ef846,g:5d655967-99ad-4791-997f-0e78f5a28c24-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/ConsolidatedBalanceSheetsunauditedParenthetical" xlink:type="simple" xlink:href="jll-20260630.xsd#ConsolidatedBalanceSheetsunauditedParenthetical"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/ConsolidatedBalanceSheetsunauditedParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e5049-32df-7059-9257-7d5c9594eea5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e5049-32df-76ee-9ed1-34c38ed5ce58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e5049-32df-7059-9257-7d5c9594eea5" xlink:to="loc_us-gaap_StatementTable_019e5049-32df-76ee-9ed1-34c38ed5ce58" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e5049-32df-70eb-9f0f-a315a2e6a2bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e5049-32df-76ee-9ed1-34c38ed5ce58" xlink:to="loc_us-gaap_CreditFacilityAxis_019e5049-32df-70eb-9f0f-a315a2e6a2bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-32df-70eb-9f0f-a315a2e6a2bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-32df-70eb-9f0f-a315a2e6a2bd" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-32df-70eb-9f0f-a315a2e6a2bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-32df-759a-b41a-b59fb21847a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-32df-70eb-9f0f-a315a2e6a2bd" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-32df-759a-b41a-b59fb21847a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e5049-32df-70c6-b1cc-7e6f7721dbc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e5049-32df-759a-b41a-b59fb21847a6" xlink:to="loc_us-gaap_LineOfCreditMember_019e5049-32df-70c6-b1cc-7e6f7721dbc5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e5049-32df-7639-9f2f-ee9d7b4829b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e5049-32df-76ee-9ed1-34c38ed5ce58" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e5049-32df-7639-9f2f-ee9d7b4829b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e5049-32df-7639-9f2f-ee9d7b4829b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e5049-32df-7639-9f2f-ee9d7b4829b7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e5049-32df-7639-9f2f-ee9d7b4829b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e5049-32df-76b4-8db7-f4234626e882" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e5049-32df-7639-9f2f-ee9d7b4829b7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e5049-32df-76b4-8db7-f4234626e882" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e5049-32df-7f39-8373-b4d85e63963f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e5049-32df-76b4-8db7-f4234626e882" xlink:to="loc_us-gaap_SeniorNotesMember_019e5049-32df-7f39-8373-b4d85e63963f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-32df-7f32-b119-0261d131a2f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e5049-32df-76ee-9ed1-34c38ed5ce58" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-32df-7f32-b119-0261d131a2f4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-32df-7f32-b119-0261d131a2f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-32df-7f32-b119-0261d131a2f4" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-32df-7f32-b119-0261d131a2f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-32df-7bd6-a0b7-82fe6414667a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-32df-7f32-b119-0261d131a2f4" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-32df-7bd6-a0b7-82fe6414667a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019e5049-32df-7637-b30c-f1259e220f0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-32df-7bd6-a0b7-82fe6414667a" xlink:to="loc_us-gaap_CommercialPaperMember_019e5049-32df-7637-b30c-f1259e220f0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LongtermseniornotesEuronotes1.96dueJune2027Member_019f956e-37a6-742a-b8a0-3544c8199a2e" xlink:href="jll-20260630.xsd#jll_LongtermseniornotesEuronotes1.96dueJune2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-32df-7bd6-a0b7-82fe6414667a" xlink:to="loc_jll_LongtermseniornotesEuronotes1.96dueJune2027Member_019f956e-37a6-742a-b8a0-3544c8199a2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-32df-7e70-99e0-5e3c54b5fc48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e5049-32df-7059-9257-7d5c9594eea5" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-32df-7e70-99e0-5e3c54b5fc48" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/ConsolidatedStatementofChangesinEquityunaudited" xlink:type="simple" xlink:href="jll-20260630.xsd#ConsolidatedStatementofChangesinEquityunaudited"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/ConsolidatedStatementofChangesinEquityunaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e5049-32df-7caa-bb76-ea13b63b1b95" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e5049-32df-72d8-adbf-6b501038f98d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e5049-32df-7caa-bb76-ea13b63b1b95" xlink:to="loc_us-gaap_StatementTable_019e5049-32df-72d8-adbf-6b501038f98d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e5049-32df-7b3b-a8b6-3c2a483f4e96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e5049-32df-72d8-adbf-6b501038f98d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e5049-32df-7b3b-a8b6-3c2a483f4e96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e5049-32df-7b3b-a8b6-3c2a483f4e96_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e5049-32df-7b3b-a8b6-3c2a483f4e96" xlink:to="loc_us-gaap_EquityComponentDomain_019e5049-32df-7b3b-a8b6-3c2a483f4e96_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e5049-32df-7b3b-a8b6-3c2a483f4e96" xlink:to="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_SharesOutstandingSoEQTDMember_019e5049-32df-7a0b-8410-12512f5ae0e0" xlink:href="jll-20260630.xsd#jll_SharesOutstandingSoEQTDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_jll_SharesOutstandingSoEQTDMember_019e5049-32df-7a0b-8410-12512f5ae0e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e5049-32df-73df-8e40-a1aade9ea905" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_us-gaap_CommonStockMember_019e5049-32df-73df-8e40-a1aade9ea905" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019e5049-32df-7101-800d-0407c1be2f9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019e5049-32df-7101-800d-0407c1be2f9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019e5049-32df-7d06-87a3-9841834236fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_us-gaap_RetainedEarningsMember_019e5049-32df-7d06-87a3-9841834236fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_SharesHeldInTrustMember_019e5049-32df-7339-8e1f-603479f0821d" xlink:href="jll-20260630.xsd#jll_SharesHeldInTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_jll_SharesHeldInTrustMember_019e5049-32df-7339-8e1f-603479f0821d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019e5049-32df-7329-9107-28a64804553a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019e5049-32df-7329-9107-28a64804553a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e5049-32df-7726-bc5d-a46abe8a42bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e5049-32df-7726-bc5d-a46abe8a42bf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019e5049-32df-7805-aa03-5b8f08d8c083" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-32df-73d5-8de3-a0d57f60c56e" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019e5049-32df-7805-aa03-5b8f08d8c083" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e5049-32df-7caa-bb76-ea13b63b1b95" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e5049-32df-762d-816c-0a8e288f1111" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e5049-32df-762d-816c-0a8e288f1111" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e5049-32df-715b-a089-272f26b10e1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019e5049-32df-715b-a089-272f26b10e1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest_019e5049-32df-7e26-b621-b9b7c3f3720d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest_019e5049-32df-7e26-b621-b9b7c3f3720d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019e5049-32df-775a-ab48-6bf5a43fdf10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019e5049-32df-775a-ab48-6bf5a43fdf10" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_VestingOfSharesRelatedToEquityCompensationPlansNetOfAmountsWithheldForPaymentOfTaxes_019e5049-32df-7243-b65f-c84726b6933b" xlink:href="jll-20260630.xsd#jll_VestingOfSharesRelatedToEquityCompensationPlansNetOfAmountsWithheldForPaymentOfTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_jll_VestingOfSharesRelatedToEquityCompensationPlansNetOfAmountsWithheldForPaymentOfTaxes_019e5049-32df-7243-b65f-c84726b6933b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019e5049-32df-75b1-b837-9f63dc34c427" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019e5049-32df-75b1-b837-9f63dc34c427" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e5049-32df-7719-b3fc-9c0bb83ec2b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e5049-32df-7719-b3fc-9c0bb83ec2b8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_IncreaseDecreaseInCommonStockHeldInTrust_019e5049-32df-7145-b08c-df1ddd5db9d0" xlink:href="jll-20260630.xsd#jll_IncreaseDecreaseInCommonStockHeldInTrust"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_jll_IncreaseDecreaseInCommonStockHeldInTrust_019e5049-32df-7145-b08c-df1ddd5db9d0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_019e5049-32df-7e1b-ae2d-0a9c2d81e507" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_019e5049-32df-7e1b-ae2d-0a9c2d81e507" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019e5049-32df-7468-899b-1108645ae60f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019e5049-32df-7468-899b-1108645ae60f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ChangeInPensionLiabilitiesNetOfTaxSoEQTD_019e5049-32df-78b6-9032-3c7cba97b32a" xlink:href="jll-20260630.xsd#jll_ChangeInPensionLiabilitiesNetOfTaxSoEQTD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_jll_ChangeInPensionLiabilitiesNetOfTaxSoEQTD_019e5049-32df-78b6-9032-3c7cba97b32a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ForeignCurrencyTranslationAdjustmentsSoEQTD_019e5049-32df-77b4-bcfd-c2e53c80cdb7" xlink:href="jll-20260630.xsd#jll_ForeignCurrencyTranslationAdjustmentsSoEQTD"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_jll_ForeignCurrencyTranslationAdjustmentsSoEQTD_019e5049-32df-77b4-bcfd-c2e53c80cdb7" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestPeriodIncreaseDecrease_019e5049-32df-743a-8a51-e627e03393ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterestPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019e5049-32df-7efd-8868-f6909d18d68d" xlink:to="loc_us-gaap_MinorityInterestPeriodIncreaseDecrease_019e5049-32df-743a-8a51-e627e03393ea" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e5049-32df-72fc-8f43-02af2c7c06f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionCharges"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7462-803b-e44755aaac1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7462-803b-e44755aaac1a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-71e1-a81f-da47cad400b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-71e1-a81f-da47cad400b3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges_1" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionCharges_1"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges_2" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionCharges_2"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-71e1-a81f-da47cad400b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-71e1-a81f-da47cad400b3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges_3" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionCharges_3"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionCharges_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-735c-adc1-b4a2a4abf1bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-735c-adc1-b4a2a4abf1bb" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7a26-8994-703ebd874a13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7004-869a-eda98ee33d74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7004-869a-eda98ee33d74" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e91-9a9c-9448b6fb3189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-77de-a4cf-7d67b6872239_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-77de-a4cf-7d67b6872239" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7746-834e-039c4a13ea9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7dd3-9c22-35192e71e420_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7dd3-9c22-35192e71e420" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7316-86ac-9c569b0a8dc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7523-8e21-e1ade8fb94ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-7523-8e21-e1ade8fb94ad" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-7215-9915-262e592e31a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7462-803b-e44755aaac1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7793-9d95-31dc0b8e71fa" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7462-803b-e44755aaac1a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7ef3-bb18-cf4568ef17de" xlink:to="loc_us-gaap_RestructuringAndRelatedActivitiesDisclosureTextBlock_019e5049-339b-719d-83c2-bc9cf1d66a62" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RevenueRecognitionDisaggregationofRevenueTables" xlink:type="simple" xlink:href="jll-20260630.xsd#RevenueRecognitionDisaggregationofRevenueTables"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RevenueRecognitionDisaggregationofRevenueTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-714c-a2c2-361d30930864" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-714c-a2c2-361d30930864" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e5049-32e0-79ef-bbca-3e51e0062e34" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:to="loc_srt_ProductOrServiceAxis_019e5049-32e0-79ef-bbca-3e51e0062e34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e5049-32e0-79ef-bbca-3e51e0062e34_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e5049-32e0-79ef-bbca-3e51e0062e34" xlink:to="loc_srt_ProductsAndServicesDomain_019e5049-32e0-79ef-bbca-3e51e0062e34_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7e95-a551-6ce8b67af1c8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e5049-32e0-79ef-bbca-3e51e0062e34" xlink:to="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7e95-a551-6ce8b67af1c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019e5049-32e0-7a48-af8c-cc7480654ee0" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:to="loc_srt_StatementGeographicalAxis_019e5049-32e0-7a48-af8c-cc7480654ee0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019e5049-32e0-7a48-af8c-cc7480654ee0_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019e5049-32e0-7a48-af8c-cc7480654ee0" xlink:to="loc_srt_SegmentGeographicalDomain_019e5049-32e0-7a48-af8c-cc7480654ee0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019e5049-32e0-7836-a2f9-ba48b1a898b2" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019e5049-32e0-7a48-af8c-cc7480654ee0" xlink:to="loc_srt_SegmentGeographicalDomain_019e5049-32e0-7836-a2f9-ba48b1a898b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_019e5049-32e0-7cd0-8468-d3a6f27da16a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_019e5049-32e0-7cd0-8468-d3a6f27da16a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_019e5049-32e0-7cd0-8468-d3a6f27da16a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_019e5049-32e0-7cd0-8468-d3a6f27da16a" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_019e5049-32e0-7cd0-8468-d3a6f27da16a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_019e5049-32e0-7112-8b7c-4ea5fd595a34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_019e5049-32e0-7cd0-8468-d3a6f27da16a" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_019e5049-32e0-7112-8b7c-4ea5fd595a34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerDurationAxis_019e5049-32e0-7c6d-8e8a-5c328b1b01a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerDurationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:to="loc_us-gaap_ContractWithCustomerDurationAxis_019e5049-32e0-7c6d-8e8a-5c328b1b01a3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerDurationDomain_019e5049-32e0-7c6d-8e8a-5c328b1b01a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerDurationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerDurationAxis_019e5049-32e0-7c6d-8e8a-5c328b1b01a3" xlink:to="loc_us-gaap_ContractWithCustomerDurationDomain_019e5049-32e0-7c6d-8e8a-5c328b1b01a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerDurationDomain_019e5049-32e0-718b-b3d3-5450821932d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerDurationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerDurationAxis_019e5049-32e0-7c6d-8e8a-5c328b1b01a3" xlink:to="loc_us-gaap_ContractWithCustomerDurationDomain_019e5049-32e0-718b-b3d3-5450821932d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019e5049-32e0-7740-8b13-68113abef22d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019e5049-32e0-7740-8b13-68113abef22d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019e5049-32e0-7740-8b13-68113abef22d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019e5049-32e0-7740-8b13-68113abef22d" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019e5049-32e0-7740-8b13-68113abef22d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019e5049-32e0-7d76-aa6b-7fc529eb627e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019e5049-32e0-7740-8b13-68113abef22d" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019e5049-32e0-7d76-aa6b-7fc529eb627e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019e5049-32e0-7a79-96d2-d1a7adb1124d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019e5049-32e0-7a79-96d2-d1a7adb1124d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019e5049-32e0-7a79-96d2-d1a7adb1124d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019e5049-32e0-7a79-96d2-d1a7adb1124d" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019e5049-32e0-7a79-96d2-d1a7adb1124d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019e5049-32e0-7d93-8f0c-8581031b6552" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019e5049-32e0-7a79-96d2-d1a7adb1124d" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019e5049-32e0-7d93-8f0c-8581031b6552" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019e5049-32e0-791d-b9a9-c70a772bde7d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-7310-a530-898a7a6d17b2" xlink:to="loc_srt_MajorCustomersAxis_019e5049-32e0-791d-b9a9-c70a772bde7d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e5049-32e0-791d-b9a9-c70a772bde7d_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019e5049-32e0-791d-b9a9-c70a772bde7d" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e5049-32e0-791d-b9a9-c70a772bde7d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e5049-32e0-7c35-ab86-c108d1fc5de3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019e5049-32e0-791d-b9a9-c70a772bde7d" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e5049-32e0-7c35-ab86-c108d1fc5de3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTableTextBlock_019e5049-32e0-7a2d-a453-c08add82fe32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-714c-a2c2-361d30930864" xlink:to="loc_us-gaap_DisaggregationOfRevenueTableTextBlock_019e5049-32e0-7a2d-a453-c08add82fe32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_019e5049-32e0-7c87-bbe4-4b516b93ad29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-714c-a2c2-361d30930864" xlink:to="loc_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_019e5049-32e0-7c87-bbe4-4b516b93ad29" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsGoodwillandOtherIntangibleAssetsTables" xlink:type="simple" xlink:href="jll-20260630.xsd#BusinessCombinationsGoodwillandOtherIntangibleAssetsTables"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsGoodwillandOtherIntangibleAssetsTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_jll_ScheduleofBusinessAcquisitionsProFormaRevenueLineItems_019e5049-32e0-729c-9e6a-1127ed8fe4a8" xlink:href="jll-20260630.xsd#jll_ScheduleofBusinessAcquisitionsProFormaRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ScheduleofBusinessAcquisitionsProFormaRevenueTable_019e5049-32e0-734c-b3b6-cb164d875307" xlink:href="jll-20260630.xsd#jll_ScheduleofBusinessAcquisitionsProFormaRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_jll_ScheduleofBusinessAcquisitionsProFormaRevenueLineItems_019e5049-32e0-729c-9e6a-1127ed8fe4a8" xlink:to="loc_jll_ScheduleofBusinessAcquisitionsProFormaRevenueTable_019e5049-32e0-734c-b3b6-cb164d875307" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock_019e5049-32e0-7f45-ab09-ced4f65ca016" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleofBusinessAcquisitionsProFormaRevenueLineItems_019e5049-32e0-729c-9e6a-1127ed8fe4a8" xlink:to="loc_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock_019e5049-32e0-7f45-ab09-ced4f65ca016" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsTables"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-78a9-abbf-5f661ee2d1a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-78a9-abbf-5f661ee2d1a1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-721b-b8c3-5b485c3d9969" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-721b-b8c3-5b485c3d9969" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables_1" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsTables_1"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables_2" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsTables_2"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-721b-b8c3-5b485c3d9969" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-721b-b8c3-5b485c3d9969" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables_3" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsTables_3"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsTables_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7961-831c-3dbcce51ef1a" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b26-adfd-3bab793a68db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-7b26-adfd-3bab793a68db" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7b20-9e4f-7d534857836d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-78a9-abbf-5f661ee2d1a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-771b-9625-97341916156a" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-78a9-abbf-5f661ee2d1a1" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-75e7-a966-1b770e36855a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-75e7-a966-1b770e36855a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-7f48-ad3b-501c20d3bea3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-7f48-ad3b-501c20d3bea3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_1" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_1"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_2" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_2"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-7f48-ad3b-501c20d3bea3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-7f48-ad3b-501c20d3bea3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_3" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_3"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesRestructuringandRelatedActivitiesTables_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-778c-af1c-b078f3541cc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e5049-339b-778c-af1c-b078f3541cc3" xlink:to="loc_srt_ConsolidationItemsDomain_019e5049-339b-7786-a5a7-1c913bd3c701" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e78-a32f-f1accff514bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7e78-a32f-f1accff514bd" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7f9e-b8f0-fa2e874105a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-7dad-9047-966a22be4974_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e5049-339b-7dad-9047-966a22be4974" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e5049-339b-72e9-b503-b159a52b6e7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7297-951b-176c02dc3244_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7297-951b-176c02dc3244" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7a75-a9ce-a2c15edc1369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-765f-b198-3be8bf605b9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019e5049-339b-765f-b198-3be8bf605b9d" xlink:to="loc_us-gaap_RestructuringPlanDomain_019e5049-339b-72a8-a753-85bca4f26ebf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-75e7-a966-1b770e36855a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f72-a2fc-2a6319676300" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-75e7-a966-1b770e36855a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock_019e5049-339b-7686-adde-9ecab353f849" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7c88-a7a1-4110f1d84cca" xlink:to="loc_us-gaap_RestructuringImpairmentAndOtherActivitiesDisclosureTextBlock_019e5049-339b-72fd-89c7-2cc06c724a60" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RevenueRecognitionRevenueRecognitionDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#RevenueRecognitionRevenueRecognitionDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RevenueRecognitionRevenueRecognitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7cd0-bbc7-22946bbc9692" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-74ba-abb0-a68e48777eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7cd0-bbc7-22946bbc9692" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-74ba-abb0-a68e48777eb5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e5049-32e0-7990-8bdb-28330bbbd994" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-74ba-abb0-a68e48777eb5" xlink:to="loc_srt_ProductOrServiceAxis_019e5049-32e0-7990-8bdb-28330bbbd994" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7990-8bdb-28330bbbd994_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e5049-32e0-7990-8bdb-28330bbbd994" xlink:to="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7990-8bdb-28330bbbd994_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7d28-a1bf-a1c8c31dc302" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e5049-32e0-7990-8bdb-28330bbbd994" xlink:to="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7d28-a1bf-a1c8c31dc302" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_OutofScopeofTopic606RevenueMember_019e5049-32e0-725c-b59f-7d702cb9804e" xlink:href="jll-20260630.xsd#jll_OutofScopeofTopic606RevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7d28-a1bf-a1c8c31dc302" xlink:to="loc_jll_OutofScopeofTopic606RevenueMember_019e5049-32e0-725c-b59f-7d702cb9804e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_019e5049-32e0-7ce9-a5ab-c56bb7c9422f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FeesAndCommissionsMortgageBankingAndServicing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7cd0-bbc7-22946bbc9692" xlink:to="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_019e5049-32e0-7ce9-a5ab-c56bb7c9422f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RevenueRecognitionContractAssetsLiabilitiesDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#RevenueRecognitionContractAssetsLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RevenueRecognitionContractAssetsLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7ad2-b3f0-d46622abb89e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-75f0-94ae-51231ecadd9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7ad2-b3f0-d46622abb89e" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-75f0-94ae-51231ecadd9d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019e5049-32e0-7dbb-acbf-39c2d9ba8252" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e5049-32e0-75f0-94ae-51231ecadd9d" xlink:to="loc_srt_ProductOrServiceAxis_019e5049-32e0-7dbb-acbf-39c2d9ba8252" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7dbb-acbf-39c2d9ba8252_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019e5049-32e0-7dbb-acbf-39c2d9ba8252" xlink:to="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7dbb-acbf-39c2d9ba8252_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7660-8c21-355f9816c1f7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019e5049-32e0-7dbb-acbf-39c2d9ba8252" xlink:to="loc_srt_ProductsAndServicesDomain_019e5049-32e0-7660-8c21-355f9816c1f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetGross_019e5049-32e0-7f57-8dc8-091167fed8a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerAssetGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7ad2-b3f0-d46622abb89e" xlink:to="loc_us-gaap_ContractWithCustomerAssetGross_019e5049-32e0-7f57-8dc8-091167fed8a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss_019e5049-32e0-724f-9612-c59b628a77f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7ad2-b3f0-d46622abb89e" xlink:to="loc_us-gaap_ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss_019e5049-32e0-724f-9612-c59b628a77f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNet_019e5049-32e0-7dda-a283-5cfa9bbff317" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerAssetNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7ad2-b3f0-d46622abb89e" xlink:to="loc_us-gaap_ContractWithCustomerAssetNet_019e5049-32e0-7dda-a283-5cfa9bbff317" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_019e5049-32e0-711e-84d4-e1c4044b94d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e5049-32e0-7ad2-b3f0-d46622abb89e" xlink:to="loc_us-gaap_ContractWithCustomerLiability_019e5049-32e0-711e-84d4-e1c4044b94d9" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/BusinessSegmentsDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#BusinessSegmentsDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/BusinessSegmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e5049-32e0-76c6-b7fd-3bb289affac8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e5049-32e0-76c6-b7fd-3bb289affac8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_BusinessLineAxis_019e5049-32e0-75a6-aa57-a77d3ba12f07" xlink:href="jll-20260630.xsd#jll_BusinessLineAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e5049-32e0-76c6-b7fd-3bb289affac8" xlink:to="loc_jll_BusinessLineAxis_019e5049-32e0-75a6-aa57-a77d3ba12f07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_BusinessLineDomain_019e5049-32e0-75a6-aa57-a77d3ba12f07_default" xlink:href="jll-20260630.xsd#jll_BusinessLineDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_jll_BusinessLineAxis_019e5049-32e0-75a6-aa57-a77d3ba12f07" xlink:to="loc_jll_BusinessLineDomain_019e5049-32e0-75a6-aa57-a77d3ba12f07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:href="jll-20260630.xsd#jll_BusinessLineDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_jll_BusinessLineAxis_019e5049-32e0-75a6-aa57-a77d3ba12f07" xlink:to="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_WorkplaceManagementMember_019e5049-32e0-7ee7-82d0-af73ff27d4bd" xlink:href="jll-20260630.xsd#jll_WorkplaceManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_WorkplaceManagementMember_019e5049-32e0-7ee7-82d0-af73ff27d4bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ProjectManagementMember_019e5049-32e0-7a60-b968-913d15867e1c" xlink:href="jll-20260630.xsd#jll_ProjectManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_ProjectManagementMember_019e5049-32e0-7a60-b968-913d15867e1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_PropertyManagementMember_019e5049-32e0-7f11-bda6-8032e57fa36e" xlink:href="jll-20260630.xsd#jll_PropertyManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_PropertyManagementMember_019e5049-32e0-7f11-bda6-8032e57fa36e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_PortfolioServicesAndOtherMember_019e5049-32e0-752a-abe7-c31193177971" xlink:href="jll-20260630.xsd#jll_PortfolioServicesAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_PortfolioServicesAndOtherMember_019e5049-32e0-752a-abe7-c31193177971" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_SoftwareAndTechnologySolutionsMember_019e5049-32e0-71e4-9d5d-c22412183163" xlink:href="jll-20260630.xsd#jll_SoftwareAndTechnologySolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_SoftwareAndTechnologySolutionsMember_019e5049-32e0-71e4-9d5d-c22412183163" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentSalesDebtEquityAdvisoryAndOtherMember_019e5049-32e0-7cd0-a695-1017c33c0a88" xlink:href="jll-20260630.xsd#jll_InvestmentSalesDebtEquityAdvisoryAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_InvestmentSalesDebtEquityAdvisoryAndOtherMember_019e5049-32e0-7cd0-a695-1017c33c0a88" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ValuationAdvisoryMember_019e5049-32e0-7618-879a-bc98eba731c0" xlink:href="jll-20260630.xsd#jll_ValuationAdvisoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_ValuationAdvisoryMember_019e5049-32e0-7618-879a-bc98eba731c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LoanServicingMember_019e5049-32e0-74e5-83da-639b5df713da" xlink:href="jll-20260630.xsd#jll_LoanServicingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_LoanServicingMember_019e5049-32e0-74e5-83da-639b5df713da" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AdvisoryFeesMember_019e5049-32e0-7c7a-bd27-2967b66d110d" xlink:href="jll-20260630.xsd#jll_AdvisoryFeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_AdvisoryFeesMember_019e5049-32e0-7c7a-bd27-2967b66d110d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_IncentiveAndTransactionFeesMember_019e5049-32e0-7b03-91a3-a11bc9055f8a" xlink:href="jll-20260630.xsd#jll_IncentiveAndTransactionFeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_BusinessLineDomain_019e5049-32e0-7d34-822c-6e63fa2ce7fc" xlink:to="loc_jll_IncentiveAndTransactionFeesMember_019e5049-32e0-7b03-91a3-a11bc9055f8a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-32e0-741f-a8a0-de9ca14c111c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e5049-32e0-76c6-b7fd-3bb289affac8" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-32e0-741f-a8a0-de9ca14c111c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-32e0-741f-a8a0-de9ca14c111c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-32e0-741f-a8a0-de9ca14c111c" xlink:to="loc_us-gaap_SegmentDomain_019e5049-32e0-741f-a8a0-de9ca14c111c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-32e0-7245-acca-07604400853e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-32e0-741f-a8a0-de9ca14c111c" xlink:to="loc_us-gaap_SegmentDomain_019e5049-32e0-7245-acca-07604400853e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_RealEstateManagementServicesMember_019e5049-32e0-737b-8d06-7dfd6cb98e07" xlink:href="jll-20260630.xsd#jll_RealEstateManagementServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-32e0-7245-acca-07604400853e" xlink:to="loc_jll_RealEstateManagementServicesMember_019e5049-32e0-737b-8d06-7dfd6cb98e07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LeasingAdvisoryMember_019e5049-32e0-7b58-a17d-7a8005ee9ecb" xlink:href="jll-20260630.xsd#jll_LeasingAdvisoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-32e0-7245-acca-07604400853e" xlink:to="loc_jll_LeasingAdvisoryMember_019e5049-32e0-7b58-a17d-7a8005ee9ecb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_CapitalMarketsServicesMember_019e5049-32e0-7a4d-8991-eb7db21b2d59" xlink:href="jll-20260630.xsd#jll_CapitalMarketsServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-32e0-7245-acca-07604400853e" xlink:to="loc_jll_CapitalMarketsServicesMember_019e5049-32e0-7a4d-8991-eb7db21b2d59" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentManagementMember_019e5049-32e0-734a-9d04-8a3f7c8032d2" xlink:href="jll-20260630.xsd#jll_InvestmentManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-32e0-7245-acca-07604400853e" xlink:to="loc_jll_InvestmentManagementMember_019e5049-32e0-734a-9d04-8a3f7c8032d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllOtherSegmentsMember_019e5049-32e0-78b2-a4b1-2fbd4aa30ac4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllOtherSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-32e0-7245-acca-07604400853e" xlink:to="loc_us-gaap_AllOtherSegmentsMember_019e5049-32e0-78b2-a4b1-2fbd4aa30ac4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e5049-32e0-7c74-8925-b511a05c7a3d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_Revenues_019e5049-32e0-7c74-8925-b511a05c7a3d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_PlatformCompensationAndBenefits_019e5049-32e0-7ca1-ae33-4b8538e0a991" xlink:href="jll-20260630.xsd#jll_PlatformCompensationAndBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_PlatformCompensationAndBenefits_019e5049-32e0-7ca1-ae33-4b8538e0a991" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_PlatformOperatingAdministrativeAndOther_019e5049-32e0-7008-9cb9-d0e99f22985d" xlink:href="jll-20260630.xsd#jll_PlatformOperatingAdministrativeAndOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_PlatformOperatingAdministrativeAndOther_019e5049-32e0-7008-9cb9-d0e99f22985d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_GrossContractCosts_019e5049-32e0-7e6f-971d-6eb544a1189d" xlink:href="jll-20260630.xsd#jll_GrossContractCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_GrossContractCosts_019e5049-32e0-7e6f-971d-6eb544a1189d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019e5049-32e0-7e85-8318-8d96d6a7a7ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_019e5049-32e0-7e85-8318-8d96d6a7a7ab" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019e5049-32e0-7c54-a0ea-0942c4523994" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019e5049-32e0-7c54-a0ea-0942c4523994" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AdjustedEBITDA_019e5049-32e0-76eb-99be-ae1065d4d982" xlink:href="jll-20260630.xsd#jll_AdjustedEBITDA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_AdjustedEBITDA_019e5049-32e0-76eb-99be-ae1065d4d982" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_019e5049-32e0-7234-b7ea-9981ca9c8ec1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_019e5049-32e0-7234-b7ea-9981ca9c8ec1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_019e5049-32e0-707e-b062-e5a2938061ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_019e5049-32e0-707e-b062-e5a2938061ce" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InterestOnEmployeeLoansNet_019e5049-32e0-7e9d-a633-4963ab2f5101" xlink:href="jll-20260630.xsd#jll_InterestOnEmployeeLoansNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_InterestOnEmployeeLoansNet_019e5049-32e0-7e9d-a633-4963ab2f5101" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EquityEarningsLossesInvestmentManagementAndSoftwareAndTechnologySolutions_019e5049-32e0-7a4d-952d-daad998ba799" xlink:href="jll-20260630.xsd#jll_EquityEarningsLossesInvestmentManagementAndSoftwareAndTechnologySolutions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_EquityEarningsLossesInvestmentManagementAndSoftwareAndTechnologySolutions_019e5049-32e0-7a4d-952d-daad998ba799" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_CreditLossesOnConvertibleNoteInvestments_019e5049-32e0-722d-9952-1c9eda3295a4" xlink:href="jll-20260630.xsd#jll_CreditLossesOnConvertibleNoteInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_CreditLossesOnConvertibleNoteInvestments_019e5049-32e0-722d-9952-1c9eda3295a4" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_NetNonCashMSRAndMortgageBankingDerivativeActivity_019e5049-32e0-76ab-b07c-d44cd2b72aa1" xlink:href="jll-20260630.xsd#jll_NetNonCashMSRAndMortgageBankingDerivativeActivity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_NetNonCashMSRAndMortgageBankingDerivativeActivity_019e5049-32e0-76ab-b07c-d44cd2b72aa1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_019e5049-32e0-77e1-b847-ee0771638fcc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_019e5049-32e0-77e1-b847-ee0771638fcc" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e5049-32e0-73d7-bc32-77671de29f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e5049-32e0-73d7-bc32-77671de29f2a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_DepreciationAndAmortizationAdjusted_019e5049-32e0-7e77-821c-f94240699d33" xlink:href="jll-20260630.xsd#jll_DepreciationAndAmortizationAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_jll_DepreciationAndAmortizationAdjusted_019e5049-32e0-7e77-821c-f94240699d33" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_019e5049-32e0-7efb-b606-2d12e48cba4b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_DepreciationAndAmortization_019e5049-32e0-7efb-b606-2d12e48cba4b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e5049-32e0-733f-a5b0-7bd5f9d60b6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019e5049-32e0-733f-a5b0-7bd5f9d60b6e" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationRevenueAbstract_019e5049-32e0-7a84-979b-8c3f38f8edba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationRevenueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_SegmentReportingInformationRevenueAbstract_019e5049-32e0-7a84-979b-8c3f38f8edba" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019e5049-32e0-7b2d-881f-6e4dd237ed55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e5049-32e0-7c27-830b-cb4084b78958" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019e5049-32e0-7b2d-881f-6e4dd237ed55" xlink:type="arc" order="19"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#BusinessCombinationsDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-791f-8e16-03ad1ff7e026" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-791f-8e16-03ad1ff7e026" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-791f-8e16-03ad1ff7e026_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-791f-8e16-03ad1ff7e026" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-791f-8e16-03ad1ff7e026_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-705a-bc98-a3f0afbe09c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-791f-8e16-03ad1ff7e026" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-705a-bc98-a3f0afbe09c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_MortgageservicingrightsMember_019e5049-339b-7da2-a845-2fea1c14a2dc" xlink:href="jll-20260630.xsd#jll_MortgageservicingrightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-705a-bc98-a3f0afbe09c5" xlink:to="loc_jll_MortgageservicingrightsMember_019e5049-339b-7da2-a845-2fea1c14a2dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019e5049-339b-738c-8ec9-12373422f0cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-705a-bc98-a3f0afbe09c5" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019e5049-339b-738c-8ec9-12373422f0cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_RedeemableNoncontrollingInterestAxis_019e5049-339b-7ffb-a3ce-487939464b40" xlink:href="jll-20260630.xsd#jll_RedeemableNoncontrollingInterestAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:to="loc_jll_RedeemableNoncontrollingInterestAxis_019e5049-339b-7ffb-a3ce-487939464b40" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_RedeemableNoncontrollingInterestDomain_019e5049-339b-7ffb-a3ce-487939464b40_default" xlink:href="jll-20260630.xsd#jll_RedeemableNoncontrollingInterestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_jll_RedeemableNoncontrollingInterestAxis_019e5049-339b-7ffb-a3ce-487939464b40" xlink:to="loc_jll_RedeemableNoncontrollingInterestDomain_019e5049-339b-7ffb-a3ce-487939464b40_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_RedeemableNoncontrollingInterestDomain_019e5049-339b-7d4f-b58c-31ffcc506208" xlink:href="jll-20260630.xsd#jll_RedeemableNoncontrollingInterestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_jll_RedeemableNoncontrollingInterestAxis_019e5049-339b-7ffb-a3ce-487939464b40" xlink:to="loc_jll_RedeemableNoncontrollingInterestDomain_019e5049-339b-7d4f-b58c-31ffcc506208" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a4c-b72d-224d290e4a6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a4c-b72d-224d290e4a6e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7a4c-b72d-224d290e4a6e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a4c-b72d-224d290e4a6e" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7a4c-b72d-224d290e4a6e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-79de-aceb-69db7ac51226" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a4c-b72d-224d290e4a6e" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-79de-aceb-69db7ac51226" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-725e-836f-83218b0d2bbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-79de-aceb-69db7ac51226" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-725e-836f-83218b0d2bbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7ebe-a29f-b851dcb0538f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7ebe-a29f-b851dcb0538f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7ebe-a29f-b851dcb0538f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7ebe-a29f-b851dcb0538f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7ebe-a29f-b851dcb0538f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7875-a9d3-06f9856cd12b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7ebe-a29f-b851dcb0538f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7875-a9d3-06f9856cd12b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-712e-898c-05acc15f7518" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7875-a9d3-06f9856cd12b" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-712e-898c-05acc15f7518" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7051-a8e0-37156fe8f0ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7051-a8e0-37156fe8f0ae" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7051-a8e0-37156fe8f0ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7051-a8e0-37156fe8f0ae" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7051-a8e0-37156fe8f0ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7e8f-822e-a3872bdac36b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7051-a8e0-37156fe8f0ae" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7e8f-822e-a3872bdac36b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019e5049-339b-7d80-acb4-6d6fa760ed94" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e5049-339b-7788-b1d2-1853c698c9d5" xlink:to="loc_srt_StatementGeographicalAxis_019e5049-339b-7d80-acb4-6d6fa760ed94" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019e5049-339b-7d80-acb4-6d6fa760ed94_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019e5049-339b-7d80-acb4-6d6fa760ed94" xlink:to="loc_srt_SegmentGeographicalDomain_019e5049-339b-7d80-acb4-6d6fa760ed94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019e5049-339b-7aba-a3d6-de646002a58b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019e5049-339b-7d80-acb4-6d6fa760ed94" xlink:to="loc_srt_SegmentGeographicalDomain_019e5049-339b-7aba-a3d6-de646002a58b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationIntegrationRelatedCosts_019e5049-339b-7b86-9bf2-a34073775249" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationIntegrationRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_BusinessCombinationIntegrationRelatedCosts_019e5049-339b-7b86-9bf2-a34073775249" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfBusinessesAcquired_019e5049-339b-72cc-8cfc-01d5c9c973b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfBusinessesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_NumberOfBusinessesAcquired_019e5049-339b-72cc-8cfc-01d5c9c973b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_PaymentforContingentConsiderationLiabilityTotal_019e5049-339b-7187-86ba-42c73f48be3f" xlink:href="jll-20260630.xsd#jll_PaymentforContingentConsiderationLiabilityTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_jll_PaymentforContingentConsiderationLiabilityTotal_019e5049-339b-7187-86ba-42c73f48be3f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e5049-339b-7d29-88be-f582c0a9d96e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e5049-339b-7d29-88be-f582c0a9d96e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_019e5049-339b-71c2-8972-c27771bcce35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_019e5049-339b-71c2-8972-c27771bcce35" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_019e5049-339b-7b6c-82e6-a0da85263331" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_019e5049-339b-7b6c-82e6-a0da85263331" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019e5049-339b-75e5-b0ce-f6396db8c512" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_019e5049-339b-75e5-b0ce-f6396db8c512" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_RedeemableNoncontrollingInterestAcquisitionDateFairValue_019f90ab-a5c2-7699-b0ff-539bffffb025" xlink:href="jll-20260630.xsd#jll_RedeemableNoncontrollingInterestAcquisitionDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_jll_RedeemableNoncontrollingInterestAcquisitionDateFairValue_019f90ab-a5c2-7699-b0ff-539bffffb025" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPaymentsToAcquireBusinesses_019e5049-339b-7a08-b35d-bb2a1f3a30f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherPaymentsToAcquireBusinesses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_OtherPaymentsToAcquireBusinesses_019e5049-339b-7a08-b35d-bb2a1f3a30f1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_BusinessCombinationsGuaranteedDeferredAcquisitionObligation_019e5049-339b-7bf4-95ff-1ab940639782" xlink:href="jll-20260630.xsd#jll_BusinessCombinationsGuaranteedDeferredAcquisitionObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_jll_BusinessCombinationsGuaranteedDeferredAcquisitionObligation_019e5049-339b-7bf4-95ff-1ab940639782" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019e5049-339b-7085-aabd-b2f5d131021c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019e5049-339b-7085-aabd-b2f5d131021c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredOther1_019e5049-339b-774c-aa6e-38dac32e0c21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationConsiderationTransferredOther1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredOther1_019e5049-339b-774c-aa6e-38dac32e0c21" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_CashPaymentsForCurrentPriorPeriodAcquisitions_019e5049-339b-71e8-b75e-c555814776bf" xlink:href="jll-20260630.xsd#jll_CashPaymentsForCurrentPriorPeriodAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e5049-339b-7c78-9a1e-8dbdb8a3a195" xlink:to="loc_jll_CashPaymentsForCurrentPriorPeriodAcquisitions_019e5049-339b-71e8-b75e-c555814776bf" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsGoodwillandOtherIntangibleAssetsBusinessCombinationsEarnoutPaymentsDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#BusinessCombinationsGoodwillandOtherIntangibleAssetsBusinessCombinationsEarnoutPaymentsDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsGoodwillandOtherIntangibleAssetsBusinessCombinationsEarnoutPaymentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_jll_SummaryofEarnoutPaymentsLineItems_019e5049-339b-7932-b3ec-0e629c848dbf" xlink:href="jll-20260630.xsd#jll_SummaryofEarnoutPaymentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_SummaryofEarnoutPaymentsTable_019e5049-339b-7a43-b738-c9075d276abb" xlink:href="jll-20260630.xsd#jll_SummaryofEarnoutPaymentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_jll_SummaryofEarnoutPaymentsLineItems_019e5049-339b-7932-b3ec-0e629c848dbf" xlink:to="loc_jll_SummaryofEarnoutPaymentsTable_019e5049-339b-7a43-b738-c9075d276abb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7b0d-9e07-fc73baf84b87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_jll_SummaryofEarnoutPaymentsTable_019e5049-339b-7a43-b738-c9075d276abb" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7b0d-9e07-fc73baf84b87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7b0d-9e07-fc73baf84b87_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7b0d-9e07-fc73baf84b87" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7b0d-9e07-fc73baf84b87_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7c8d-ae49-cc90b083496f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7b0d-9e07-fc73baf84b87" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7c8d-ae49-cc90b083496f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7a93-afe5-6b9b32fd8c26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7c8d-ae49-cc90b083496f" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7a93-afe5-6b9b32fd8c26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-771f-996d-ae0a8e91c3fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_jll_SummaryofEarnoutPaymentsTable_019e5049-339b-7a43-b738-c9075d276abb" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-771f-996d-ae0a8e91c3fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-771f-996d-ae0a8e91c3fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-771f-996d-ae0a8e91c3fd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-771f-996d-ae0a8e91c3fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-748b-a574-38287a6d6845" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-771f-996d-ae0a8e91c3fd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-748b-a574-38287a6d6845" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-77ac-a097-ffbf0dc4edd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-748b-a574-38287a6d6845" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-77ac-a097-ffbf0dc4edd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_NumberOfAcquisitionsSubjectToPotentialEarnOutPaymentsProvisions_019e5049-339b-7ce7-91fb-d114f5dd5102" xlink:href="jll-20260630.xsd#jll_NumberOfAcquisitionsSubjectToPotentialEarnOutPaymentsProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_SummaryofEarnoutPaymentsLineItems_019e5049-339b-7932-b3ec-0e629c848dbf" xlink:to="loc_jll_NumberOfAcquisitionsSubjectToPotentialEarnOutPaymentsProvisions_019e5049-339b-7ce7-91fb-d114f5dd5102" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesHighValue_019e5049-339b-7f91-a813-02b92debe7d0" xlink:href="jll-20260630.xsd#jll_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesHighValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_SummaryofEarnoutPaymentsLineItems_019e5049-339b-7932-b3ec-0e629c848dbf" xlink:to="loc_jll_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesHighValue_019e5049-339b-7f91-a813-02b92debe7d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_019e5049-339b-760e-af18-223a56b6130e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_SummaryofEarnoutPaymentsLineItems_019e5049-339b-7932-b3ec-0e629c848dbf" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_019e5049-339b-760e-af18-223a56b6130e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_019e5049-339b-7ce3-aae8-550ee7cac3ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_SummaryofEarnoutPaymentsLineItems_019e5049-339b-7932-b3ec-0e629c848dbf" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_019e5049-339b-7ce3-aae8-550ee7cac3ed" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsGoodwillbySegmentDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#BusinessCombinationsGoodwillbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsGoodwillbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019e5049-339b-73be-8b20-214d0eb48be6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019e5049-339b-78b0-a696-c2cf079a52c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019e5049-339b-73be-8b20-214d0eb48be6" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019e5049-339b-78b0-a696-c2cf079a52c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7d8e-b2e2-7c5a0e52de33" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e5049-339b-78b0-a696-c2cf079a52c2" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7d8e-b2e2-7c5a0e52de33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-7d8e-b2e2-7c5a0e52de33_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7d8e-b2e2-7c5a0e52de33" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-7d8e-b2e2-7c5a0e52de33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-75c5-9a0e-79f58fe591c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-7d8e-b2e2-7c5a0e52de33" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-75c5-9a0e-79f58fe591c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LeasingAdvisoryMember_019e5049-339b-7dd1-befe-67776cffa9d2" xlink:href="jll-20260630.xsd#jll_LeasingAdvisoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-339b-75c5-9a0e-79f58fe591c6" xlink:to="loc_jll_LeasingAdvisoryMember_019e5049-339b-7dd1-befe-67776cffa9d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_CapitalMarketsServicesMember_019e5049-339b-745f-9d4c-0052be94c1f5" xlink:href="jll-20260630.xsd#jll_CapitalMarketsServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-339b-75c5-9a0e-79f58fe591c6" xlink:to="loc_jll_CapitalMarketsServicesMember_019e5049-339b-745f-9d4c-0052be94c1f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_RealEstateManagementServicesMember_019e5049-339b-73c7-8a67-f384da7f3fa2" xlink:href="jll-20260630.xsd#jll_RealEstateManagementServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-339b-75c5-9a0e-79f58fe591c6" xlink:to="loc_jll_RealEstateManagementServicesMember_019e5049-339b-73c7-8a67-f384da7f3fa2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ProptechInvestmentsMember_019e5049-339b-7a6d-9f80-b0cbff41cf9f" xlink:href="jll-20260630.xsd#jll_ProptechInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-339b-75c5-9a0e-79f58fe591c6" xlink:to="loc_jll_ProptechInvestmentsMember_019e5049-339b-7a6d-9f80-b0cbff41cf9f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentManagementMember_019e5049-339b-7d5d-89ce-f822f3e06c06" xlink:href="jll-20260630.xsd#jll_InvestmentManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e5049-339b-75c5-9a0e-79f58fe591c6" xlink:to="loc_jll_InvestmentManagementMember_019e5049-339b-7d5d-89ce-f822f3e06c06" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-76c7-87c7-9299b1434886" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e5049-339b-78b0-a696-c2cf079a52c2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-76c7-87c7-9299b1434886" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-76c7-87c7-9299b1434886_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-76c7-87c7-9299b1434886" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-76c7-87c7-9299b1434886_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-7c80-85c5-4fef4dc7a601" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-76c7-87c7-9299b1434886" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-7c80-85c5-4fef4dc7a601" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019e5049-339b-73e4-a814-ceddbf3c9387" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-7c80-85c5-4fef4dc7a601" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019e5049-339b-73e4-a814-ceddbf3c9387" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_MortgageservicingrightsMember_019e5049-339b-7b4b-967e-27a7b358856d" xlink:href="jll-20260630.xsd#jll_MortgageservicingrightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-7c80-85c5-4fef4dc7a601" xlink:to="loc_jll_MortgageservicingrightsMember_019e5049-339b-7b4b-967e-27a7b358856d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019e5049-339b-7f67-82da-1a1d34dee8a1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e5049-339b-78b0-a696-c2cf079a52c2" xlink:to="loc_srt_StatementGeographicalAxis_019e5049-339b-7f67-82da-1a1d34dee8a1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019e5049-339b-7f67-82da-1a1d34dee8a1_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019e5049-339b-7f67-82da-1a1d34dee8a1" xlink:to="loc_srt_SegmentGeographicalDomain_019e5049-339b-7f67-82da-1a1d34dee8a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019e5049-339b-7610-bff5-725db51206cf" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019e5049-339b-7f67-82da-1a1d34dee8a1" xlink:to="loc_srt_SegmentGeographicalDomain_019e5049-339b-7610-bff5-725db51206cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AmericasMember_019e5049-339b-7720-9174-dfb9f8876ea0" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AmericasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019e5049-339b-7610-bff5-725db51206cf" xlink:to="loc_srt_AmericasMember_019e5049-339b-7720-9174-dfb9f8876ea0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EMEAMember_019e5049-339b-7c55-aeba-ec44ae19195c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EMEAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019e5049-339b-7610-bff5-725db51206cf" xlink:to="loc_us-gaap_EMEAMember_019e5049-339b-7c55-aeba-ec44ae19195c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaPacificMember_019e5049-339b-7c2e-ab41-3b652b7c0352" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019e5049-339b-7610-bff5-725db51206cf" xlink:to="loc_srt_AsiaPacificMember_019e5049-339b-7c2e-ab41-3b652b7c0352" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_019e5049-339b-7266-8688-d652356e2054" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e5049-339b-73be-8b20-214d0eb48be6" xlink:to="loc_us-gaap_GoodwillRollForward_019e5049-339b-7266-8688-d652356e2054" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e5049-339b-71a8-937c-326c8ce77add" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e5049-339b-7266-8688-d652356e2054" xlink:to="loc_us-gaap_Goodwill_019e5049-339b-71a8-937c-326c8ce77add" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_GoodwillAdditionsNetOfAdjustments_019e5049-339b-7729-83b3-75c260b4d007" xlink:href="jll-20260630.xsd#jll_GoodwillAdditionsNetOfAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e5049-339b-7266-8688-d652356e2054" xlink:to="loc_jll_GoodwillAdditionsNetOfAdjustments_019e5049-339b-7729-83b3-75c260b4d007" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_019e5049-339b-709f-98a9-3b164e3e2c7a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e5049-339b-7266-8688-d652356e2054" xlink:to="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_019e5049-339b-709f-98a9-3b164e3e2c7a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_019e5049-339b-71ff-be2a-86a2613a6152" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e5049-339b-7266-8688-d652356e2054" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_019e5049-339b-71ff-be2a-86a2613a6152" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e5049-339b-7a4e-bced-625766fb53ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsOtherIntangiblesbySegmentDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#BusinessCombinationsOtherIntangiblesbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/BusinessCombinationsOtherIntangiblesbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:href="jll-20260630.xsd#jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentTable_019e5049-339b-7734-ac62-a9d611ca48c7" xlink:href="jll-20260630.xsd#jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentTable_019e5049-339b-7734-ac62-a9d611ca48c7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-7e28-8e37-68e2a593a143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentTable_019e5049-339b-7734-ac62-a9d611ca48c7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-7e28-8e37-68e2a593a143" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-7e28-8e37-68e2a593a143_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-7e28-8e37-68e2a593a143" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-7e28-8e37-68e2a593a143_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-70c7-b223-27a5d1cdd7fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e5049-339b-7e28-8e37-68e2a593a143" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-70c7-b223-27a5d1cdd7fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_MortgageservicingrightsMember_019e5049-339b-78c7-84af-3f11c6ef7e38" xlink:href="jll-20260630.xsd#jll_MortgageservicingrightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-70c7-b223-27a5d1cdd7fa" xlink:to="loc_jll_MortgageservicingrightsMember_019e5049-339b-78c7-84af-3f11c6ef7e38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019e5049-339b-70b7-85b1-1f6c03d05c68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e5049-339b-70c7-b223-27a5d1cdd7fa" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019e5049-339b-70b7-85b1-1f6c03d05c68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-77a2-babc-5d548c36dae8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentTable_019e5049-339b-7734-ac62-a9d611ca48c7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-77a2-babc-5d548c36dae8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-77a2-babc-5d548c36dae8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-77a2-babc-5d548c36dae8" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-77a2-babc-5d548c36dae8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e5049-339b-74c6-9fae-e44879fa86c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e5049-339b-77a2-babc-5d548c36dae8" xlink:to="loc_us-gaap_SegmentDomain_019e5049-339b-74c6-9fae-e44879fa86c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019e5049-339b-7879-89a0-2b44a6817b15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019e5049-339b-7879-89a0-2b44a6817b15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019e5049-339b-7501-95f0-e4b4d0c7b797" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019e5049-339b-7501-95f0-e4b4d0c7b797" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_FiniteAndIndefiniteLivedIntangibleAssetsAdditions_019e5049-339b-77c6-b1fb-9ec1f2e87ab0" xlink:href="jll-20260630.xsd#jll_FiniteAndIndefiniteLivedIntangibleAssetsAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_jll_FiniteAndIndefiniteLivedIntangibleAssetsAdditions_019e5049-339b-77c6-b1fb-9ec1f2e87ab0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AdjustmentForFullyAmortizedIntangibles_019e5049-339b-7506-b245-fd4612d018c9" xlink:href="jll-20260630.xsd#jll_AdjustmentForFullyAmortizedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_jll_AdjustmentForFullyAmortizedIntangibles_019e5049-339b-7506-b245-fd4612d018c9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_019e5049-339b-7a01-856a-5c58321847b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill_019e5049-339b-7a01-856a-5c58321847b1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019e5049-339b-797a-ae8c-9ec224005df3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019e5049-339b-797a-ae8c-9ec224005df3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_FiniteAndIndefiniteLivedIntangibleAssetsTranslationAdjustments_019e5049-339b-7a0d-92f3-560ae48d1c69" xlink:href="jll-20260630.xsd#jll_FiniteAndIndefiniteLivedIntangibleAssetsTranslationAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_jll_FiniteAndIndefiniteLivedIntangibleAssetsTranslationAdjustments_019e5049-339b-7a0d-92f3-560ae48d1c69" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019e5049-339b-7aa0-9f7e-56b617c7aba2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019e5049-339b-7aa0-9f7e-56b617c7aba2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e5049-339b-7864-8ead-3c2f19b9fb5f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e5049-339b-7864-8ead-3c2f19b9fb5f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019e5049-339b-7cfa-8c6f-0472e4245cb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019e5049-339b-7cfa-8c6f-0472e4245cb9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AccumulatedAmortizationAdjustmentforfullyAmortizedIntangibles_019e5049-339b-7da1-b8e8-816ffdec9d4a" xlink:href="jll-20260630.xsd#jll_AccumulatedAmortizationAdjustmentforfullyAmortizedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_jll_AccumulatedAmortizationAdjustmentforfullyAmortizedIntangibles_019e5049-339b-7da1-b8e8-816ffdec9d4a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AccumulatedAmortizationFiniteLivedIntangibleAssetsTranslationAdjustments_019e5049-339b-7610-b053-2947b6e3e232" xlink:href="jll-20260630.xsd#jll_AccumulatedAmortizationFiniteLivedIntangibleAssetsTranslationAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_jll_AccumulatedAmortizationFiniteLivedIntangibleAssetsTranslationAdjustments_019e5049-339b-7610-b053-2947b6e3e232" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e5049-339b-7752-a926-2e8977a362df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e5049-339b-7752-a926-2e8977a362df" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedCostOtherThanTemporaryImpairments_019e5049-339b-7874-9a8a-0c657548f63f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ServicingAssetAtAmortizedCostOtherThanTemporaryImpairments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_ServicingAssetAtAmortizedCostOtherThanTemporaryImpairments_019e5049-339b-7874-9a8a-0c657548f63f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtAmortizedCostOtherThanTemporaryImpairments_019e5049-339b-728f-9468-e215c8fc5491" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ServicingAssetAtAmortizedCostOtherThanTemporaryImpairments"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceForImpairmentOfRecognizedServicingAssetsAggregateWriteDowns_019e5049-339b-777e-b2b6-316350ad6686" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationAllowanceForImpairmentOfRecognizedServicingAssetsAggregateWriteDowns"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_ValuationAllowanceForImpairmentOfRecognizedServicingAssetsAggregateWriteDowns_019e5049-339b-777e-b2b6-316350ad6686" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_ScheduleOfFiniteAndIndefiniteLivedIntangibleAssetsBySegmentLineItems_019e5049-339b-7368-ba5d-123f09d308ee" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_019e5049-339b-755f-ac95-b1af7da85c19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_019e5049-339b-755f-ac95-b1af7da85c19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_019e5049-339b-7b8b-9ce1-6a1c94f12ae6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_019e5049-339b-7b8b-9ce1-6a1c94f12ae6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_019e5049-339b-7ea6-ad99-ec39753cfb8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_019e5049-339b-7ea6-ad99-ec39753cfb8b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_019e5049-339b-7f47-975b-c480e4bf90fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_019e5049-339b-7f47-975b-c480e4bf90fd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_019e5049-339b-77c1-b905-6b6bbaf1723b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_019e5049-339b-77c1-b905-6b6bbaf1723b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_019e5049-339b-718e-97c1-7e8804b39758" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_019e5049-339b-718e-97c1-7e8804b39758" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_019e5049-339b-75bc-afef-89ad095d0b3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseCurrentAndFiveSucceedingFiscalYearsAbstract_019e5049-339b-7313-8cbf-07388c9490e6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_019e5049-339b-75bc-afef-89ad095d0b3b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019e5049-339b-72b7-9d17-ca35469bf9c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019e5049-339b-7a05-9453-3f7de26358e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/InvestmentsDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#InvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/InvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e5049-339b-74e4-95e5-0aa6dd8ffc08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e5049-339b-74e4-95e5-0aa6dd8ffc08" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e5049-339b-7105-912d-2cace0c68cd4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e5049-339b-74e4-95e5-0aa6dd8ffc08" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e5049-339b-7105-912d-2cace0c68cd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-7105-912d-2cace0c68cd4_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e5049-339b-7105-912d-2cace0c68cd4" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-7105-912d-2cace0c68cd4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-724e-8b40-45a1edef8159" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019e5049-339b-7105-912d-2cace0c68cd4" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-724e-8b40-45a1edef8159" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentManagementMember_019e5049-339b-79e2-992f-465ee8a6bd5d" xlink:href="jll-20260630.xsd#jll_InvestmentManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-724e-8b40-45a1edef8159" xlink:to="loc_jll_InvestmentManagementMember_019e5049-339b-79e2-992f-465ee8a6bd5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ProptechInvestmentsMember_019e5049-339b-7afb-897c-b6d3658761c9" xlink:href="jll-20260630.xsd#jll_ProptechInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-724e-8b40-45a1edef8159" xlink:to="loc_jll_ProptechInvestmentsMember_019e5049-339b-7afb-897c-b6d3658761c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_OtherInvestmentsAndAdvanceToAffiliatesSubsidiariesAssociatesAndJointVenturesMember_019e5049-339b-78a8-89d5-48cf0b50b42c" xlink:href="jll-20260630.xsd#jll_OtherInvestmentsAndAdvanceToAffiliatesSubsidiariesAssociatesAndJointVenturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-724e-8b40-45a1edef8159" xlink:to="loc_jll_OtherInvestmentsAndAdvanceToAffiliatesSubsidiariesAssociatesAndJointVenturesMember_019e5049-339b-78a8-89d5-48cf0b50b42c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_SoftwareAndTechnologySolutionsMember_019f8aa2-33fa-7c48-8c53-8938cf7b2806" xlink:href="jll-20260630.xsd#jll_SoftwareAndTechnologySolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019e5049-339b-724e-8b40-45a1edef8159" xlink:to="loc_jll_SoftwareAndTechnologySolutionsMember_019f8aa2-33fa-7c48-8c53-8938cf7b2806" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-776e-b08c-a1231a675d63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e5049-339b-74e4-95e5-0aa6dd8ffc08" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-776e-b08c-a1231a675d63" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-776e-b08c-a1231a675d63_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-776e-b08c-a1231a675d63" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-776e-b08c-a1231a675d63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7cd2-90ed-57911da388d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-776e-b08c-a1231a675d63" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7cd2-90ed-57911da388d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7423-9f5b-ac8a531bbd94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7cd2-90ed-57911da388d8" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7423-9f5b-ac8a531bbd94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7c85-a687-07d01d513061" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e5049-339b-74e4-95e5-0aa6dd8ffc08" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7c85-a687-07d01d513061" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7c85-a687-07d01d513061_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7c85-a687-07d01d513061" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7c85-a687-07d01d513061_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-78d4-863e-f4a3f7839d27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7c85-a687-07d01d513061" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-78d4-863e-f4a3f7839d27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-72da-92bb-ba8469924ba6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-78d4-863e-f4a3f7839d27" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-72da-92bb-ba8469924ba6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7b5b-bdce-35e7f2217e96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_019e5049-339b-74e4-95e5-0aa6dd8ffc08" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7b5b-bdce-35e7f2217e96" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7b5b-bdce-35e7f2217e96_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7b5b-bdce-35e7f2217e96" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7b5b-bdce-35e7f2217e96_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7727-bd97-8e3fe99bcf14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7b5b-bdce-35e7f2217e96" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7727-bd97-8e3fe99bcf14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsMember_019e5049-339b-7ed3-b28d-a876871aaa1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7727-bd97-8e3fe99bcf14" xlink:to="loc_us-gaap_InvestmentsMember_019e5049-339b-7ed3-b28d-a876871aaa1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_NumberOfSeparatePropertyOrFundCoInvestments_019e5049-339b-75c1-a2df-5365b4f3138c" xlink:href="jll-20260630.xsd#jll_NumberOfSeparatePropertyOrFundCoInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:to="loc_jll_NumberOfSeparatePropertyOrFundCoInvestments_019e5049-339b-75c1-a2df-5365b4f3138c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsMaximumExposure_019e5049-339b-7216-8061-8b6996b7ee8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GuaranteeObligationsMaximumExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:to="loc_us-gaap_GuaranteeObligationsMaximumExposure_019e5049-339b-7216-8061-8b6996b7ee8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_019e5049-339b-7351-9181-874da316c283" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_019e5049-339b-7351-9181-874da316c283" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:href="jll-20260630.xsd#jll_FairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:to="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-724c-ae3d-1aeb59d33efe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-724c-ae3d-1aeb59d33efe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentsinRealEstateVenturesatFairValueAdditions_019e5049-339b-76d6-90ce-3d7298130570" xlink:href="jll-20260630.xsd#jll_InvestmentsinRealEstateVenturesatFairValueAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:to="loc_jll_InvestmentsinRealEstateVenturesatFairValueAdditions_019e5049-339b-76d6-90ce-3d7298130570" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentsinRealEstateVenturesatFairValueDistributions_019e5049-339b-77ca-8cdf-de10ad235dc4" xlink:href="jll-20260630.xsd#jll_InvestmentsinRealEstateVenturesatFairValueDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:to="loc_jll_InvestmentsinRealEstateVenturesatFairValueDistributions_019e5049-339b-77ca-8cdf-de10ad235dc4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnInvestments_019e5049-339b-774e-b37c-18f6f1192ccf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:to="loc_us-gaap_UnrealizedGainLossOnInvestments_019e5049-339b-774e-b37c-18f6f1192ccf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentsinRealEstateVenturesatFairValueForeignCurrencyTranslation_019e5049-339b-79db-ac26-8c367fc92322" xlink:href="jll-20260630.xsd#jll_InvestmentsinRealEstateVenturesatFairValueForeignCurrencyTranslation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:to="loc_jll_InvestmentsinRealEstateVenturesatFairValueForeignCurrencyTranslation_019e5049-339b-79db-ac26-8c367fc92322" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_InvestmentsPreviouslyAccountedAtCostThatAreNowBeingAccountedForAtNetAssetValue_019e5049-339b-7749-8acb-f402a20e3493" xlink:href="jll-20260630.xsd#jll_InvestmentsPreviouslyAccountedAtCostThatAreNowBeingAccountedForAtNetAssetValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_FairValueAbstract_019e5049-339b-714b-8c86-c13eebbcbf8c" xlink:to="loc_jll_InvestmentsPreviouslyAccountedAtCostThatAreNowBeingAccountedForAtNetAssetValue_019e5049-339b-7749-8acb-f402a20e3493" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7d14-b416-479484535266" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EquityInvestmentsAccountedForUnderTheMeasurementAlternative_019e5049-339b-7ba3-bc5f-085c4c3bb079" xlink:href="jll-20260630.xsd#jll_EquityInvestmentsAccountedForUnderTheMeasurementAlternative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:to="loc_jll_EquityInvestmentsAccountedForUnderTheMeasurementAlternative_019e5049-339b-7ba3-bc5f-085c4c3bb079" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_019e5049-339b-7e01-9b2f-2ace5991ac6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_019e5049-339b-7e3d-94e4-9f9ccb50333b" xlink:to="loc_us-gaap_AssetImpairmentCharges_019e5049-339b-7e01-9b2f-2ace5991ac6c" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/StockbasedCompensationDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#StockbasedCompensationDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/StockbasedCompensationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e5049-339b-718a-896e-a1fb4b8df792" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e5049-339b-7ddc-ae43-90464109a102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e5049-339b-718a-896e-a1fb4b8df792" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e5049-339b-7ddc-ae43-90464109a102" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e5049-339b-7ef8-baff-964807e53952" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e5049-339b-7ddc-ae43-90464109a102" xlink:to="loc_us-gaap_AwardTypeAxis_019e5049-339b-7ef8-baff-964807e53952" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e5049-339b-7ef8-baff-964807e53952_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e5049-339b-7ef8-baff-964807e53952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e5049-339b-7ef8-baff-964807e53952_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e5049-339b-79ce-a4c3-b4a94f4b95e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e5049-339b-7ef8-baff-964807e53952" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e5049-339b-79ce-a4c3-b4a94f4b95e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e5049-339b-72ec-b696-1ba9daabedb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e5049-339b-79ce-a4c3-b4a94f4b95e4" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e5049-339b-72ec-b696-1ba9daabedb8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019e5049-339b-7506-a7b4-578f47962b03" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e5049-339b-79ce-a4c3-b4a94f4b95e4" xlink:to="loc_us-gaap_PerformanceSharesMember_019e5049-339b-7506-a7b4-578f47962b03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019e5049-339b-7768-b352-15f55c0ae903" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e5049-339b-79ce-a4c3-b4a94f4b95e4" xlink:to="loc_us-gaap_StockCompensationPlanMember_019e5049-339b-7768-b352-15f55c0ae903" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019f8a6a-1627-76db-98e6-e43b086117fb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e5049-339b-7ddc-ae43-90464109a102" xlink:to="loc_srt_ProductOrServiceAxis_019f8a6a-1627-76db-98e6-e43b086117fb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f8a6a-1627-76db-98e6-e43b086117fb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019f8a6a-1627-76db-98e6-e43b086117fb" xlink:to="loc_srt_ProductsAndServicesDomain_019f8a6a-1627-76db-98e6-e43b086117fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f8a6a-1627-7efb-bd45-5297c73baed9" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019f8a6a-1627-76db-98e6-e43b086117fb" xlink:to="loc_srt_ProductsAndServicesDomain_019f8a6a-1627-7efb-bd45-5297c73baed9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_OutofScopeofTopic606RevenueMember_019f8a6a-1627-79f4-a4ca-8fd475fd079c" xlink:href="jll-20260630.xsd#jll_OutofScopeofTopic606RevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f8a6a-1627-7efb-bd45-5297c73baed9" xlink:to="loc_jll_OutofScopeofTopic606RevenueMember_019f8a6a-1627-79f4-a4ca-8fd475fd079c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e5049-339b-71ea-94e8-37978d4c55bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e5049-339b-718a-896e-a1fb4b8df792" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e5049-339b-71ea-94e8-37978d4c55bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e5049-339b-73ae-a3c6-91764a656d3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e5049-339b-71ea-94e8-37978d4c55bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e5049-339b-73ae-a3c6-91764a656d3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e5049-339b-7b9a-a8a0-750dd8162dee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e5049-339b-71ea-94e8-37978d4c55bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e5049-339b-7b9a-a8a0-750dd8162dee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e5049-339b-7599-871e-f9992962f36c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e5049-339b-71ea-94e8-37978d4c55bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e5049-339b-7599-871e-f9992962f36c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e5049-339b-7afa-acca-f4b940234cf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e5049-339b-71ea-94e8-37978d4c55bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e5049-339b-7afa-acca-f4b940234cf5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e5049-339b-7af0-bb9e-c52ad1a5a5de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e5049-339b-718a-896e-a1fb4b8df792" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e5049-339b-77d4-9cc6-6a0f1897fdbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e5049-339b-77d4-9cc6-6a0f1897fdbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e5049-339b-7840-92bf-4d096c4e8241" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e5049-339b-7840-92bf-4d096c4e8241" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e5049-339b-7ddc-b7d4-f48ade5020c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e5049-339b-7ddc-b7d4-f48ade5020c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e5049-339b-7637-aa34-ee232b12f890" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e5049-339b-7637-aa34-ee232b12f890" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e5049-339b-7b49-bcdd-b729504641be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_019e5049-339b-71c4-9127-bfb79b8ae777" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_019e5049-339b-71c4-9127-bfb79b8ae777" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019e5049-339b-7103-a0ab-19db4fa05bf8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e5049-339b-7354-85c3-16f1b0ac7e54" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019e5049-339b-7103-a0ab-19db4fa05bf8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_019f8a6a-1627-7af2-bb5a-ffbab3e678c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FeesAndCommissionsMortgageBankingAndServicing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e5049-339b-718a-896e-a1fb4b8df792" xlink:to="loc_us-gaap_FeesAndCommissionsMortgageBankingAndServicing_019f8a6a-1627-7af2-bb5a-ffbab3e678c3" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7579-b6bd-515db531b8e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7579-b6bd-515db531b8e7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a14-83f9-560f3a31ba0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7579-b6bd-515db531b8e7" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a14-83f9-560f3a31ba0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7a14-83f9-560f3a31ba0a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a14-83f9-560f3a31ba0a" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7a14-83f9-560f3a31ba0a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7ce5-b24e-1be984687380" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7a14-83f9-560f3a31ba0a" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7ce5-b24e-1be984687380" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7a62-aa5c-43611df6cab4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7ce5-b24e-1be984687380" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7a62-aa5c-43611df6cab4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-746b-97d0-28f790d6b9e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7579-b6bd-515db531b8e7" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-746b-97d0-28f790d6b9e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-746b-97d0-28f790d6b9e7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-746b-97d0-28f790d6b9e7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-746b-97d0-28f790d6b9e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-71dc-9ef8-a8707fa9803c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-746b-97d0-28f790d6b9e7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-71dc-9ef8-a8707fa9803c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019e5049-339b-78a5-be89-8c04940e5ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-71dc-9ef8-a8707fa9803c" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019e5049-339b-78a5-be89-8c04940e5ce4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-723e-8224-c9f9b4569c58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7579-b6bd-515db531b8e7" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-723e-8224-c9f9b4569c58" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-723e-8224-c9f9b4569c58_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-723e-8224-c9f9b4569c58" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-723e-8224-c9f9b4569c58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d4d-86a4-0cdd42a81ff8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-723e-8224-c9f9b4569c58" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d4d-86a4-0cdd42a81ff8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019e5049-339b-7ee0-865f-0e5a3f94582c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d4d-86a4-0cdd42a81ff8" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_019e5049-339b-7ee0-865f-0e5a3f94582c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e5049-339b-7b73-bfcc-5da79f39de53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d4d-86a4-0cdd42a81ff8" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e5049-339b-7b73-bfcc-5da79f39de53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7529-96b2-4f270eece7e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d4d-86a4-0cdd42a81ff8" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7529-96b2-4f270eece7e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-7648-a751-a47e41c86b98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7579-b6bd-515db531b8e7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-7648-a751-a47e41c86b98" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7648-a751-a47e41c86b98_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-7648-a751-a47e41c86b98" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7648-a751-a47e41c86b98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7d87-be63-46fa8b8b4061" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-7648-a751-a47e41c86b98" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7d87-be63-46fa8b8b4061" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e5049-339b-7530-9e09-a152fbd95333" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7d87-be63-46fa8b8b4061" xlink:to="loc_us-gaap_SeniorNotesMember_019e5049-339b-7530-9e09-a152fbd95333" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-77b1-b081-649221081f10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7579-b6bd-515db531b8e7" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-77b1-b081-649221081f10" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-77b1-b081-649221081f10_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-77b1-b081-649221081f10" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-77b1-b081-649221081f10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7436-8743-b23cdbc527b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-77b1-b081-649221081f10" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7436-8743-b23cdbc527b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_019e5049-339b-727b-ad79-a2b4d1463b86" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7436-8743-b23cdbc527b9" xlink:to="loc_us-gaap_DerivativeMember_019e5049-339b-727b-ad79-a2b4d1463b86" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7254-8cf5-d99c855c1e9f" xlink:href="jll-20260630.xsd#jll_EarnoutLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7436-8743-b23cdbc527b9" xlink:to="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7254-8cf5-d99c855c1e9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsMember_019e5049-339b-7134-b640-4723403aaf02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7436-8743-b23cdbc527b9" xlink:to="loc_us-gaap_InvestmentsMember_019e5049-339b-7134-b640-4723403aaf02" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_019e5049-339b-751a-9287-23e8d30aedf7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_LongTermDebtFairValue_019e5049-339b-751a-9287-23e8d30aedf7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotes_019f9bc3-f9f6-79ec-8b0d-000aff596ec7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_SeniorNotes_019f9bc3-f9f6-79ec-8b0d-000aff596ec7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorLongTermNotes_019e5049-339b-7d64-9c46-0661df070da1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorLongTermNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_SeniorLongTermNotes_019e5049-339b-7d64-9c46-0661df070da1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e5049-339b-7042-915d-b66601ef70d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e5049-339b-7042-915d-b66601ef70d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ForeignCurrencyForwardContractNetNotionalValue_019e5049-339b-780f-9136-7a2bd2433100" xlink:href="jll-20260630.xsd#jll_ForeignCurrencyForwardContractNetNotionalValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_jll_ForeignCurrencyForwardContractNetNotionalValue_019e5049-339b-780f-9136-7a2bd2433100" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7c49-89b4-f5d4a50ece7f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7c49-89b4-f5d4a50ece7f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_019e5049-339b-7249-a4d9-e6da61262206" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyContractAssetFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_019e5049-339b-7249-a4d9-e6da61262206" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e5049-339b-7937-ba31-0d5b428580b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e5049-339b-7937-ba31-0d5b428580b8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e5049-339b-7c04-9a16-0110d54e64a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e5049-339b-7c04-9a16-0110d54e64a4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_019e5049-339b-771f-ace1-7c6e4ea16904" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_019e5049-339b-771f-ace1-7c6e4ea16904" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e5049-339b-7a0c-94da-9ef8e1f85f77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e5049-339b-7a0c-94da-9ef8e1f85f77" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e5049-339b-7cf8-9432-8da8180f4ed2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e5049-339b-7cf8-9432-8da8180f4ed2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_DeferredCompensationPlanAssetsFairValueDisclosure_019e5049-339b-729d-bdc2-3d5b400cf122" xlink:href="jll-20260630.xsd#jll_DeferredCompensationPlanAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_jll_DeferredCompensationPlanAssetsFairValueDisclosure_019e5049-339b-729d-bdc2-3d5b400cf122" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_019e5049-339b-7366-8793-6f6123c64ac4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_019e5049-339b-7366-8793-6f6123c64ac4" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockIssuedEmployeeStockTrust_019e5049-339b-7b1f-ae87-95eee71909e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockIssuedEmployeeStockTrust"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_CommonStockIssuedEmployeeStockTrust_019e5049-339b-7b1f-ae87-95eee71909e2" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019e5049-339b-7bd7-93fa-caecf7a8ba1f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_LongTermDebtCurrent_019e5049-339b-7bd7-93fa-caecf7a8ba1f" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7064-b947-ee5839ccd74b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-7020-89ac-a3753163a942" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7064-b947-ee5839ccd74b" xlink:type="arc" order="16"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsAssetsandLiabilitiesMeasuredonaRecurringBasisDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsAssetsandLiabilitiesMeasuredonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsAssetsandLiabilitiesMeasuredonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7367-9909-eb1a28ee101d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7367-9909-eb1a28ee101d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7dd6-882c-53af2ed8d194" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7367-9909-eb1a28ee101d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7dd6-882c-53af2ed8d194" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7dd6-882c-53af2ed8d194_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7dd6-882c-53af2ed8d194" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7dd6-882c-53af2ed8d194_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7f2b-9273-96fd64ccdac0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7dd6-882c-53af2ed8d194" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7f2b-9273-96fd64ccdac0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsMember_019e5049-339b-7ee3-8c24-e422906dc9ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7f2b-9273-96fd64ccdac0" xlink:to="loc_us-gaap_InvestmentsMember_019e5049-339b-7ee3-8c24-e422906dc9ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_019e5049-339b-7c3a-9daa-18429c31d5bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7f2b-9273-96fd64ccdac0" xlink:to="loc_us-gaap_DerivativeMember_019e5049-339b-7c3a-9daa-18429c31d5bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-78f9-a189-274ff056daa5" xlink:href="jll-20260630.xsd#jll_EarnoutLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7f2b-9273-96fd64ccdac0" xlink:to="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-78f9-a189-274ff056daa5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7fa0-9d18-8a2536f5e31f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7367-9909-eb1a28ee101d" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7fa0-9d18-8a2536f5e31f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7fa0-9d18-8a2536f5e31f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7fa0-9d18-8a2536f5e31f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7fa0-9d18-8a2536f5e31f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-756b-9dce-36fa3e5ccf81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7fa0-9d18-8a2536f5e31f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-756b-9dce-36fa3e5ccf81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e5049-339b-73e6-abd0-1cec3546f9d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-756b-9dce-36fa3e5ccf81" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e5049-339b-73e6-abd0-1cec3546f9d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e5049-339b-7231-8686-eba5bab6649c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-756b-9dce-36fa3e5ccf81" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e5049-339b-7231-8686-eba5bab6649c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e48-aad1-e6062aa703c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-756b-9dce-36fa3e5ccf81" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e48-aad1-e6062aa703c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7ddf-bf36-fae40aa66868" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e5049-339b-7367-9909-eb1a28ee101d" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7ddf-bf36-fae40aa66868" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7ddf-bf36-fae40aa66868_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7ddf-bf36-fae40aa66868" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7ddf-bf36-fae40aa66868_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-71fc-9dd0-10d76572fd29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-7ddf-bf36-fae40aa66868" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-71fc-9dd0-10d76572fd29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7171-bcce-e17e02918ed5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-71fc-9dd0-10d76572fd29" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7171-bcce-e17e02918ed5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7824-a59c-4df7cb21bfd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7824-a59c-4df7cb21bfd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7287-a0bc-5bf786017c6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7287-a0bc-5bf786017c6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_019e5049-339b-782a-863a-1b8509611e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyContractAssetFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_019e5049-339b-782a-863a-1b8509611e8a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e5049-339b-7932-8a1b-ebdb482915bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e5049-339b-7932-8a1b-ebdb482915bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_019e5049-339b-735d-9f16-64a8fa6f350d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_019e5049-339b-735d-9f16-64a8fa6f350d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_DeferredCompensationPlanAssetsFairValueDisclosure_019e5049-339b-782c-b34b-f53b45de1a30" xlink:href="jll-20260630.xsd#jll_DeferredCompensationPlanAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_jll_DeferredCompensationPlanAssetsFairValueDisclosure_019e5049-339b-782c-b34b-f53b45de1a30" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e5049-339b-789d-b9ec-ce25115aa050" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_DerivativeAssets_019e5049-339b-789d-b9ec-ce25115aa050" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019e5049-339b-74f8-8b9c-4ff6f77de992" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019e5049-339b-74f8-8b9c-4ff6f77de992" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_019e5049-339b-7bd0-98dd-2186e781dea7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_019e5049-339b-7bd0-98dd-2186e781dea7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e5049-339b-747d-89b3-9183cda90726" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e5049-339b-747d-89b3-9183cda90726" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_019e5049-339b-704a-b9c8-30f6b285daca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_019e5049-339b-704a-b9c8-30f6b285daca" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7883-8f06-f1e12e26ad71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7883-8f06-f1e12e26ad71" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e5049-339b-719a-9716-55158e2d28d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_DerivativeLiabilities_019e5049-339b-719a-9716-55158e2d28d4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_019e5049-339b-7fc2-a62d-ad5377243acb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_019e5049-339b-7fc2-a62d-ad5377243acb" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-74aa-85b2-fe7bfa2ccd4b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-74aa-85b2-fe7bfa2ccd4b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-788d-9547-7d14d1954400" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-788d-9547-7d14d1954400" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-751a-b154-3726addc3d5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-751a-b154-3726addc3d5c" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-76dd-be66-2e5033aad4a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-76dd-be66-2e5033aad4a1" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-7988-9a75-a3ac8a316a10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e5049-339b-72b8-be09-5f44c0335232" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-7988-9a75-a3ac8a316a10" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:href="jll-20260630.xsd#jll_EarnoutLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7e84-8a00-136d04edac4b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7e84-8a00-136d04edac4b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-79de-9bdb-0b6f250a4c48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-79de-9bdb-0b6f250a4c48" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7a3f-acea-813c7a719922" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7286-a590-6bc48b521f58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_1" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_1"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:href="jll-20260630.xsd#jll_EarnoutLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7a3f-acea-813c7a719922" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7286-a590-6bc48b521f58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_2" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_2"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:href="jll-20260630.xsd#jll_EarnoutLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7e84-8a00-136d04edac4b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e5049-339b-7e84-8a00-136d04edac4b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7a3f-acea-813c7a719922" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7286-a590-6bc48b521f58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_3" xlink:type="simple" xlink:href="jll-20260630.xsd#FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_3"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/FairValueMeasurementsFairValueMeasurementsReconciliationofAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7446-9f23-bf29c58a85d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e5049-339b-7446-9f23-bf29c58a85d2" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:href="jll-20260630.xsd#jll_EarnoutLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_jll_EarnoutLiabilitiesMember_019e5049-339b-7a30-9ff2-201010b25d8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_DerivativeMember_019e5049-339b-7720-a6eb-0f14e6991bf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e5049-339b-7bb7-8191-bfb832675320" xlink:to="loc_us-gaap_InvestmentsMember_019e5049-339b-7c51-bed3-471765600aee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-77f0-ab96-4a95c1dfa44b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e5049-339b-77f0-ab96-4a95c1dfa44b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e5049-339b-7d8c-bc5a-ebdcb20dfb5c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e5049-339b-7d73-9b1b-883642c7c934" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-7d73-8a16-03e83154ab38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e5049-339b-7d73-8a16-03e83154ab38" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e5049-339b-792a-bcad-13c7dbbe40f4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e5049-339b-7e38-9ee4-18c884c41326" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-72bb-af51-0f8b2d3dc5c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019e5049-339b-72bb-af51-0f8b2d3dc5c7" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019e5049-339b-7e56-9397-986189b47c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-79de-9bdb-0b6f250a4c48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019e5049-339b-75ec-98a1-db4fe30701b8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeBalanceAxis_019e5049-339b-79de-9bdb-0b6f250a4c48" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_019e5049-339b-7cd9-8184-c75363633b8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019e5049-339b-7233-bf48-a6c19736f219" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7c0a-9968-76eda1da923e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7f80-a392-8d4103bff102" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_019e5049-339b-714c-8119-cd8e136387dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_019e5049-339b-7d6f-896e-c6e36aca7cc7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases_019e5049-339b-7913-b068-2a065bd5b486" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements_019e5049-339b-7c4a-94a9-357050cb3e6b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3_019e5049-339b-707f-98bf-2d65aa53684b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_019e5049-339b-7494-b9f6-b54fcedf0079" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_019e5049-339b-70f5-a5b9-d013eacacc2f" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet_019e5049-339b-7fc8-a6a1-cdb49a1d91e5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e5049-339b-7a3f-acea-813c7a719922" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_019e5049-339b-7286-a590-6bc48b521f58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/DebtShortTermBorrowingsandLongTermDebtDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#DebtShortTermBorrowingsandLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/DebtShortTermBorrowingsandLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e5049-339b-7fe5-ba06-2a23f444ee43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_DebtInstrumentTable_019e5049-339b-7fe5-ba06-2a23f444ee43" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-724d-b94c-b4fa772929ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e5049-339b-7fe5-ba06-2a23f444ee43" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-724d-b94c-b4fa772929ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-724d-b94c-b4fa772929ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-724d-b94c-b4fa772929ea" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-724d-b94c-b4fa772929ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7f33-b3c8-22a9a38c056b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e5049-339b-724d-b94c-b4fa772929ea" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7f33-b3c8-22a9a38c056b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LongtermseniornotesEuronotes1.96dueJune2027Member_019e5049-339b-72f7-ab18-cc4dddfb0387" xlink:href="jll-20260630.xsd#jll_LongtermseniornotesEuronotes1.96dueJune2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7f33-b3c8-22a9a38c056b" xlink:to="loc_jll_LongtermseniornotesEuronotes1.96dueJune2027Member_019e5049-339b-72f7-ab18-cc4dddfb0387" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LongtermseniornotesEuronotes2.21dueJune2029Member_019e5049-339b-7ca7-b79f-1740344b3914" xlink:href="jll-20260630.xsd#jll_LongtermseniornotesEuronotes2.21dueJune2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7f33-b3c8-22a9a38c056b" xlink:to="loc_jll_LongtermseniornotesEuronotes2.21dueJune2029Member_019e5049-339b-7ca7-b79f-1740344b3914" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LongTermSeniorNotes6.875DueDecember2028Member_019e5049-339b-7012-a391-30327a5cd615" xlink:href="jll-20260630.xsd#jll_LongTermSeniorNotes6.875DueDecember2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e5049-339b-7f33-b3c8-22a9a38c056b" xlink:to="loc_jll_LongTermSeniorNotes6.875DueDecember2028Member_019e5049-339b-7012-a391-30327a5cd615" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e5049-339b-76f0-b797-7befc1086cb0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e5049-339b-7fe5-ba06-2a23f444ee43" xlink:to="loc_us-gaap_CreditFacilityAxis_019e5049-339b-76f0-b797-7befc1086cb0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-339b-76f0-b797-7befc1086cb0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-339b-76f0-b797-7befc1086cb0" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-339b-76f0-b797-7befc1086cb0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-339b-72c0-83fc-3a711fad2284" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-339b-76f0-b797-7befc1086cb0" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-339b-72c0-83fc-3a711fad2284" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e5049-339b-7801-84fe-a8bbdf36c19d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e5049-339b-72c0-83fc-3a711fad2284" xlink:to="loc_us-gaap_LineOfCreditMember_019e5049-339b-7801-84fe-a8bbdf36c19d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019e5049-339b-7a85-95a1-3bcfa58a81e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e5049-339b-72c0-83fc-3a711fad2284" xlink:to="loc_us-gaap_CommercialPaperMember_019e5049-339b-7a85-95a1-3bcfa58a81e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-772a-a198-13f013229bd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e5049-339b-7fe5-ba06-2a23f444ee43" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-772a-a198-13f013229bd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-772a-a198-13f013229bd1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-772a-a198-13f013229bd1" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-772a-a198-13f013229bd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-7427-8fb9-3f42ff0e4557" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-772a-a198-13f013229bd1" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-7427-8fb9-3f42ff0e4557" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019e5049-339b-761d-b96f-4b1bac3c43b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-7427-8fb9-3f42ff0e4557" xlink:to="loc_us-gaap_CommercialPaperMember_019e5049-339b-761d-b96f-4b1bac3c43b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LongtermseniornotesEuronotes1.96dueJune2027Member_019f8ab8-cbac-74e6-bdb0-cf3ae81ad91a" xlink:href="jll-20260630.xsd#jll_LongtermseniornotesEuronotes1.96dueJune2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-7427-8fb9-3f42ff0e4557" xlink:to="loc_jll_LongtermseniornotesEuronotes1.96dueJune2027Member_019f8ab8-cbac-74e6-bdb0-cf3ae81ad91a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankOverdrafts_019e5049-339b-756e-a99c-ecae379b7689" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BankOverdrafts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_BankOverdrafts_019e5049-339b-756e-a99c-ecae379b7689" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherShortTermBorrowings_019e5049-339b-7dc5-bae9-3d52b8ad2366" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_OtherShortTermBorrowings_019e5049-339b-7dc5-bae9-3d52b8ad2366" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaper_019e5049-339b-7878-b910-47b021d96827" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaper"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_CommercialPaper_019e5049-339b-7878-b910-47b021d96827" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_019e5049-339b-762b-b9aa-fa5c935e8695" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_ShortTermBorrowings_019e5049-339b-762b-b9aa-fa5c935e8695" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorLongTermNotes_019e5049-339b-7743-914a-93412459ce2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorLongTermNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_SeniorLongTermNotes_019e5049-339b-7743-914a-93412459ce2d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_019e5049-339b-72fd-9f70-87d2f9fa875e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtLongtermAndShorttermCombinedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_019e5049-339b-72fd-9f70-87d2f9fa875e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019e5049-339b-7dd8-93e6-09b1359678c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019e5049-339b-7dd8-93e6-09b1359678c6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e5049-339b-7a06-8e32-2f8d0c99ff84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e5049-339b-7a06-8e32-2f8d0c99ff84" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-339b-7053-b991-f2dfe9faa018" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-339b-7053-b991-f2dfe9faa018" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e5049-339b-7755-a5b8-c1cb8a4e54d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e5049-339b-7755-a5b8-c1cb8a4e54d5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019f8aaf-24cb-7c54-b176-d8088ea6e0d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e5049-339b-72aa-b236-347ad5d5aad8" xlink:to="loc_us-gaap_LongTermDebtCurrent_019f8aaf-24cb-7c54-b176-d8088ea6e0d7" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/CreditFacilityDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#CreditFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/CreditFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7825-8f9c-addecaadba14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7825-8f9c-addecaadba14" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-77f0-b192-c243e14c63e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7825-8f9c-addecaadba14" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-77f0-b192-c243e14c63e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-77f0-b192-c243e14c63e1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-77f0-b192-c243e14c63e1" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-77f0-b192-c243e14c63e1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-75eb-8433-9ddcaf7e90b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019e5049-339b-77f0-b192-c243e14c63e1" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019e5049-339b-75eb-8433-9ddcaf7e90b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7758-b783-5ca8f5cee569" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7825-8f9c-addecaadba14" xlink:to="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7758-b783-5ca8f5cee569" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-339b-7758-b783-5ca8f5cee569_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7758-b783-5ca8f5cee569" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-339b-7758-b783-5ca8f5cee569_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-339b-70e9-a38f-ad5c3b1ba2c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7758-b783-5ca8f5cee569" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-339b-70e9-a38f-ad5c3b1ba2c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019e5049-339b-78f5-a79e-e10cd8ba90bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e5049-339b-70e9-a38f-ad5c3b1ba2c0" xlink:to="loc_us-gaap_LineOfCreditMember_019e5049-339b-78f5-a79e-e10cd8ba90bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-339b-70c8-a6c6-a2ea2e9630e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-339b-70c8-a6c6-a2ea2e9630e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LongtermLineofCreditNoncurrentNetofDebtIssuanceCosts_019e5049-339b-7d72-af0e-4badd56c7d7a" xlink:href="jll-20260630.xsd#jll_LongtermLineofCreditNoncurrentNetofDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_jll_LongtermLineofCreditNoncurrentNetofDebtIssuanceCosts_019e5049-339b-7d72-af0e-4badd56c7d7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e5049-339b-72e7-94dc-1ec50854da7d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e5049-339b-72e7-94dc-1ec50854da7d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_019e5049-339b-7097-a4bb-220d77591edb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityAverageOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_019e5049-339b-7097-a4bb-220d77591edb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_019e5049-339b-7fa4-a865-0d13fb10ac3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_019e5049-339b-7fa4-a865-0d13fb10ac3a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_019e5049-339b-7c84-aa43-57a397884198" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityInterestRateDescription"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_019e5049-339b-7c84-aa43-57a397884198" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e5049-339b-7a3f-8de2-e1d0b0564024" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e5049-339b-7a3f-8de2-e1d0b0564024" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_UncommittedFacilityMaximumBorrowingCapacity_019e5049-339b-7d14-97b1-c7541a6acef9" xlink:href="jll-20260630.xsd#jll_UncommittedFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-7a55-82f9-384d6cc110c4" xlink:to="loc_jll_UncommittedFacilityMaximumBorrowingCapacity_019e5049-339b-7d14-97b1-c7541a6acef9" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/DebtWarehouseFacilitiesDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#DebtWarehouseFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/DebtWarehouseFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7e81-9b4d-fede3b1894c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7e81-9b4d-fede3b1894c7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7c6d-8c23-4c8ae2b648e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7e81-9b4d-fede3b1894c7" xlink:to="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7c6d-8c23-4c8ae2b648e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-339b-7c6d-8c23-4c8ae2b648e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7c6d-8c23-4c8ae2b648e3" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-339b-7c6d-8c23-4c8ae2b648e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e5049-339b-7939-bd7b-9fe13255f008" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e5049-339b-7c6d-8c23-4c8ae2b648e3" xlink:to="loc_us-gaap_CreditFacilityDomain_019e5049-339b-7939-bd7b-9fe13255f008" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarehouseAgreementBorrowingsMember_019e5049-339b-74df-9054-2bafc759259f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarehouseAgreementBorrowingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e5049-339b-7939-bd7b-9fe13255f008" xlink:to="loc_us-gaap_WarehouseAgreementBorrowingsMember_019e5049-339b-74df-9054-2bafc759259f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LineOfCreditFacilityByTypeAxis_019e5049-339b-7433-a69b-1a214a36e508" xlink:href="jll-20260630.xsd#jll_LineOfCreditFacilityByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019e5049-339b-7e81-9b4d-fede3b1894c7" xlink:to="loc_jll_LineOfCreditFacilityByTypeAxis_019e5049-339b-7433-a69b-1a214a36e508" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7433-a69b-1a214a36e508_default" xlink:href="jll-20260630.xsd#jll_LineOfCreditFacilityByTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_jll_LineOfCreditFacilityByTypeAxis_019e5049-339b-7433-a69b-1a214a36e508" xlink:to="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7433-a69b-1a214a36e508_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7cf8-a4e6-61680816bee1" xlink:href="jll-20260630.xsd#jll_LineOfCreditFacilityByTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_jll_LineOfCreditFacilityByTypeAxis_019e5049-339b-7433-a69b-1a214a36e508" xlink:to="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7cf8-a4e6-61680816bee1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AgreementExpiresSeptember142026ExtensionMember_019e5049-339b-73b5-9bb6-d9b1d0a47c76" xlink:href="jll-20260630.xsd#jll_AgreementExpiresSeptember142026ExtensionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7cf8-a4e6-61680816bee1" xlink:to="loc_jll_AgreementExpiresSeptember142026ExtensionMember_019e5049-339b-73b5-9bb6-d9b1d0a47c76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AgreementExpiresSeptember112026ExtensionMember_019e5049-339b-70a8-b35d-ed832ddd6e65" xlink:href="jll-20260630.xsd#jll_AgreementExpiresSeptember112026ExtensionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7cf8-a4e6-61680816bee1" xlink:to="loc_jll_AgreementExpiresSeptember112026ExtensionMember_019e5049-339b-70a8-b35d-ed832ddd6e65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_AgreementExpiresOctober222026ExtensionMember_019e5049-339b-74de-bde1-d2504b5e7595" xlink:href="jll-20260630.xsd#jll_AgreementExpiresOctober222026ExtensionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7cf8-a4e6-61680816bee1" xlink:to="loc_jll_AgreementExpiresOctober222026ExtensionMember_019e5049-339b-74de-bde1-d2504b5e7595" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_FannieMaeASAPprogramMember_019e5049-339b-772a-b39f-273b83071229" xlink:href="jll-20260630.xsd#jll_FannieMaeASAPprogramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7cf8-a4e6-61680816bee1" xlink:to="loc_jll_FannieMaeASAPprogramMember_019e5049-339b-772a-b39f-273b83071229" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LineofCreditGrossMember_019e5049-339b-72c0-b5fe-b410777e90b8" xlink:href="jll-20260630.xsd#jll_LineofCreditGrossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_jll_LineOfCreditFacilityByTypeDomain_019e5049-339b-7cf8-a4e6-61680816bee1" xlink:to="loc_jll_LineofCreditGrossMember_019e5049-339b-72c0-b5fe-b410777e90b8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditCurrent_019e5049-339b-7fdd-937b-d0862c17be15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LinesOfCreditCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_LinesOfCreditCurrent_019e5049-339b-7fdd-937b-d0862c17be15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e5049-339b-7a40-abaa-a61741342d52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e5049-339b-7a40-abaa-a61741342d52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_019e5049-339b-71f0-b22e-ef1ea0df8d14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityInterestRateDescription"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDescription_019e5049-339b-71f0-b22e-ef1ea0df8d14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-339b-77ba-8416-248444ccccb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019e5049-339b-77ba-8416-248444ccccb9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarehouseAgreementBorrowings_019e5049-339b-7066-8494-1c896929a33b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarehouseAgreementBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_WarehouseAgreementBorrowings_019e5049-339b-7066-8494-1c896929a33b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale_019e5049-339b-7ac0-9d13-9b0a177e107c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale_019e5049-339b-7ac0-9d13-9b0a177e107c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleAndCollectionOfLoansHeldforsale_019e5049-339b-7b67-82e6-5df64919c44a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleAndCollectionOfLoansHeldforsale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_us-gaap_ProceedsFromSaleAndCollectionOfLoansHeldforsale_019e5049-339b-7b67-82e6-5df64919c44a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_NetIncreaseDecreaseInWarehouseFacilities_019e5049-339b-7630-841d-726491d25e65" xlink:href="jll-20260630.xsd#jll_NetIncreaseDecreaseInWarehouseFacilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019e5049-339b-79bf-8290-46b343c120ff" xlink:to="loc_jll_NetIncreaseDecreaseInWarehouseFacilities_019e5049-339b-7630-841d-726491d25e65" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e5049-339b-7110-a625-eac4e0309796" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e5049-339b-7008-99eb-f4a8b03c6287" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e5049-339b-7110-a625-eac4e0309796" xlink:to="loc_us-gaap_LossContingenciesTable_019e5049-339b-7008-99eb-f4a8b03c6287" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e5049-339b-7986-9369-96ccb9852471" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e5049-339b-7008-99eb-f4a8b03c6287" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e5049-339b-7986-9369-96ccb9852471" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e5049-339b-7986-9369-96ccb9852471_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e5049-339b-7986-9369-96ccb9852471" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e5049-339b-7986-9369-96ccb9852471_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e5049-339b-7989-957e-5ef020330385" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e5049-339b-7986-9369-96ccb9852471" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e5049-339b-7989-957e-5ef020330385" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceClaimsMember_019e5049-339b-7533-bf3d-5f12c107ffcb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InsuranceClaimsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e5049-339b-7989-957e-5ef020330385" xlink:to="loc_us-gaap_InsuranceClaimsMember_019e5049-339b-7533-bf3d-5f12c107ffcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualRollForward_019e5049-339b-719a-9027-9ac362f7cea7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e5049-339b-7110-a625-eac4e0309796" xlink:to="loc_us-gaap_LossContingencyAccrualRollForward_019e5049-339b-719a-9027-9ac362f7cea7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019e5049-339b-7f62-b980-deb7d1588cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_019e5049-339b-719a-9027-9ac362f7cea7" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019e5049-339b-7f62-b980-deb7d1588cb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyLossInPeriod_019e5049-339b-7bfa-9f1f-c34ea8a0d667" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyLossInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_019e5049-339b-719a-9027-9ac362f7cea7" xlink:to="loc_us-gaap_LossContingencyLossInPeriod_019e5049-339b-7bfa-9f1f-c34ea8a0d667" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_LossContingencyAccrualProvisionAdjustment_019e5049-339b-7799-b73d-16cee2cfd28f" xlink:href="jll-20260630.xsd#jll_LossContingencyAccrualProvisionAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_019e5049-339b-719a-9027-9ac362f7cea7" xlink:to="loc_jll_LossContingencyAccrualProvisionAdjustment_019e5049-339b-7799-b73d-16cee2cfd28f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualPayments_019e5049-339b-711f-b8b3-b112646c8b2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyAccrualRollForward_019e5049-339b-719a-9027-9ac362f7cea7" xlink:to="loc_us-gaap_LossContingencyAccrualPayments_019e5049-339b-711f-b8b3-b112646c8b2c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019e5049-339b-7562-8f05-103c35428d6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_019e5049-339b-7a03-8803-ba685ac87b72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e5049-339b-7110-a625-eac4e0309796" xlink:to="loc_us-gaap_LossContingencyReceivable_019e5049-339b-7a03-8803-ba685ac87b72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_EstimatedLossOnLoanRepurchase_019e5049-339b-75ab-b525-21e55fa2ab0b" xlink:href="jll-20260630.xsd#jll_EstimatedLossOnLoanRepurchase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e5049-339b-7110-a625-eac4e0309796" xlink:to="loc_jll_EstimatedLossOnLoanRepurchase_019e5049-339b-75ab-b525-21e55fa2ab0b" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#RestructuringandAcquisitionChargesDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/RestructuringandAcquisitionChargesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f6e-b8a4-22c1e1461658" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f6e-b8a4-22c1e1461658" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7169-bd3d-0a0c20fc3a28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019e5049-339b-7f6e-b8a4-22c1e1461658" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7169-bd3d-0a0c20fc3a28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7169-bd3d-0a0c20fc3a28_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7169-bd3d-0a0c20fc3a28" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7169-bd3d-0a0c20fc3a28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7c02-bd11-437919b1527f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019e5049-339b-7169-bd3d-0a0c20fc3a28" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7c02-bd11-437919b1527f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019e5049-339b-794f-baa6-d173352cd6fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7c02-bd11-437919b1527f" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019e5049-339b-794f-baa6-d173352cd6fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractTerminationMember_019e5049-339b-7156-996f-1cc66ddc1d76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractTerminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7c02-bd11-437919b1527f" xlink:to="loc_us-gaap_ContractTerminationMember_019e5049-339b-7156-996f-1cc66ddc1d76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringMember_019e5049-339b-7cb8-b346-ae228081bc93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherRestructuringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7c02-bd11-437919b1527f" xlink:to="loc_us-gaap_OtherRestructuringMember_019e5049-339b-7cb8-b346-ae228081bc93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ContractTerminationAndOtherChargesMember_019e5049-339b-7803-b637-89e9c5ba0bc6" xlink:href="jll-20260630.xsd#jll_ContractTerminationAndOtherChargesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019e5049-339b-7c02-bd11-437919b1527f" xlink:to="loc_jll_ContractTerminationAndOtherChargesMember_019e5049-339b-7803-b637-89e9c5ba0bc6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationIntegrationRelatedCosts_019e5049-339b-7c5c-8f90-aeb475fe7082" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationIntegrationRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:to="loc_us-gaap_BusinessCombinationIntegrationRelatedCosts_019e5049-339b-7c5c-8f90-aeb475fe7082" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_019e5049-339b-7eaa-90db-392450e38646" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:to="loc_us-gaap_RestructuringReserveRollForward_019e5049-339b-7eaa-90db-392450e38646" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019e5049-339b-7515-a3e6-158ac09df17e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019e5049-339b-7eaa-90db-392450e38646" xlink:to="loc_us-gaap_RestructuringReserve_019e5049-339b-7515-a3e6-158ac09df17e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_019e5049-339b-7bc0-8c15-dd18d99bf1c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019e5049-339b-7eaa-90db-392450e38646" xlink:to="loc_us-gaap_PaymentsForRestructuring_019e5049-339b-7bc0-8c15-dd18d99bf1c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019e5049-339b-7bc1-987f-eed4b0ec46c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserve"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019e5049-339b-73be-9aa3-0e684a0131f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:to="loc_us-gaap_RestructuringCharges_019e5049-339b-73be-9aa3-0e684a0131f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019e5049-339b-7c85-bbf8-7c1bbf2968da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:to="loc_us-gaap_ShareBasedCompensation_019e5049-339b-7c85-bbf8-7c1bbf2968da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019e5049-339b-7b48-b98a-9bfb545f401a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019e5049-339b-7b48-b98a-9bfb545f401a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_019e5049-339b-710e-a0b7-55c939627796" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostsAndAssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019e5049-339b-7007-92a1-be283cc05d41" xlink:to="loc_us-gaap_RestructuringCostsAndAssetImpairmentCharges_019e5049-339b-710e-a0b7-55c939627796" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/AccumulatedOtherComprehensiveIncomeLossbyComponentDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#AccumulatedOtherComprehensiveIncomeLossbyComponentDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/AccumulatedOtherComprehensiveIncomeLossbyComponentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e5049-339b-7bcd-ad85-9f4716f7bce4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e5049-339b-7bcd-ad85-9f4716f7bce4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e5049-339b-7124-abe7-3315790dc2f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e5049-339b-7bcd-ad85-9f4716f7bce4" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e5049-339b-7124-abe7-3315790dc2f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e5049-339b-7124-abe7-3315790dc2f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e5049-339b-7124-abe7-3315790dc2f1" xlink:to="loc_us-gaap_EquityComponentDomain_019e5049-339b-7124-abe7-3315790dc2f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e5049-339b-7121-85c2-cd52ca8b7f53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e5049-339b-7124-abe7-3315790dc2f1" xlink:to="loc_us-gaap_EquityComponentDomain_019e5049-339b-7121-85c2-cd52ca8b7f53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e5049-339b-76ec-9377-cb6283a858d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-339b-7121-85c2-cd52ca8b7f53" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e5049-339b-76ec-9377-cb6283a858d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e5049-339b-7054-803e-5a33f9d9625e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-339b-7121-85c2-cd52ca8b7f53" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e5049-339b-7054-803e-5a33f9d9625e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e5049-339b-79ad-a5ce-a3a9a7fb43fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e5049-339b-7121-85c2-cd52ca8b7f53" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e5049-339b-79ad-a5ce-a3a9a7fb43fa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e5049-339b-74f1-b2bb-e8fa611f6590" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e5049-339b-74f1-b2bb-e8fa611f6590" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e5049-339b-7609-9822-3475e6c582d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e5049-339b-7609-9822-3475e6c582d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e5049-339b-7fec-9572-2f6ae1c4a28e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e5049-339b-7fec-9572-2f6ae1c4a28e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_019e5049-339b-7916-84b8-b688dcd55ffd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_019e5049-339b-7916-84b8-b688dcd55ffd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_019e5049-339b-71db-baa5-03f84e85fbf3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_019e5049-339b-71db-baa5-03f84e85fbf3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e5049-339b-7999-8127-8d448f2a1292" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e5049-339b-78cd-a714-4bae8b691110" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019e5049-339b-7999-8127-8d448f2a1292" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.us.amjoneslanglasalle.com/role/DerivativeInstrumentsandHedgingActivitiesDetails" xlink:type="simple" xlink:href="jll-20260630.xsd#DerivativeInstrumentsandHedgingActivitiesDetails"/>
  <link:definitionLink xlink:role="http://www.us.amjoneslanglasalle.com/role/DerivativeInstrumentsandHedgingActivitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e5049-339b-7d7d-bc3b-77f43ac40f22" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e5049-339b-7d7d-bc3b-77f43ac40f22" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-7dbf-99fe-79db7e951aa4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e5049-339b-7d7d-bc3b-77f43ac40f22" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-7dbf-99fe-79db7e951aa4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-7dbf-99fe-79db7e951aa4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-7dbf-99fe-79db7e951aa4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-7dbf-99fe-79db7e951aa4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-7890-9acc-2f0b4225b3da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e5049-339b-7dbf-99fe-79db7e951aa4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-7890-9acc-2f0b4225b3da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForwardContractsMember_019e5049-339b-77aa-ac9a-f8f4924e887f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForwardContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-7890-9acc-2f0b4225b3da" xlink:to="loc_us-gaap_ForwardContractsMember_019e5049-339b-77aa-ac9a-f8f4924e887f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e5049-339b-7094-9334-bfb4348e3683" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e5049-339b-7890-9acc-2f0b4225b3da" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e5049-339b-7094-9334-bfb4348e3683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e5049-339b-7b89-9907-7979ff6dcc94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e5049-339b-7d7d-bc3b-77f43ac40f22" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e5049-339b-7b89-9907-7979ff6dcc94" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e5049-339b-7b89-9907-7979ff6dcc94_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e5049-339b-7b89-9907-7979ff6dcc94" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e5049-339b-7b89-9907-7979ff6dcc94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e5049-339b-74a7-a648-f01c2952daa0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e5049-339b-7b89-9907-7979ff6dcc94" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e5049-339b-74a7-a648-f01c2952daa0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e5049-339b-7a97-acbd-661d21dc344d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019e5049-339b-7d7d-bc3b-77f43ac40f22" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e5049-339b-7a97-acbd-661d21dc344d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e5049-339b-7a97-acbd-661d21dc344d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e5049-339b-7a97-acbd-661d21dc344d" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e5049-339b-7a97-acbd-661d21dc344d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e5049-339b-7fbf-9f73-539c5be8dce9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e5049-339b-7a97-acbd-661d21dc344d" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e5049-339b-7fbf-9f73-539c5be8dce9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e5049-339b-7e0e-973a-d25bc981bc9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e5049-339b-7e0e-973a-d25bc981bc9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_ForeignCurrencyForwardContractNetNotionalValue_019e5049-339b-7a75-a29b-29d8f81ffd07" xlink:href="jll-20260630.xsd#jll_ForeignCurrencyForwardContractNetNotionalValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_jll_ForeignCurrencyForwardContractNetNotionalValue_019e5049-339b-7a75-a29b-29d8f81ffd07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e5049-339b-7cba-9b2e-63a11991da53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019e5049-339b-7cba-9b2e-63a11991da53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e5049-339b-718a-999e-1543ee828418" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019e5049-339b-718a-999e-1543ee828418" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e5049-339b-70cd-b133-9ed7c066fba6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_019e5049-339b-70cd-b133-9ed7c066fba6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e5049-339b-79cb-863f-0e539c147e4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_019e5049-339b-79cb-863f-0e539c147e4f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019e5049-339b-7815-a0aa-edf05d15e2a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeAssets_019e5049-339b-7815-a0aa-edf05d15e2a8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019e5049-339b-7bae-b892-3984c7f67e4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeLiabilities_019e5049-339b-7bae-b892-3984c7f67e4f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_019e5049-339b-79b7-ba59-9686f421d225" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_019e5049-339b-79b7-ba59-9686f421d225" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_DerivativeFairValueNetLiability_019e5049-339b-7915-b2c3-2245e64a3f0e" xlink:href="jll-20260630.xsd#jll_DerivativeFairValueNetLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_jll_DerivativeFairValueNetLiability_019e5049-339b-7915-b2c3-2245e64a3f0e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_019e5049-339b-7453-8fc4-80c73be7a0c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_019e5049-339b-7453-8fc4-80c73be7a0c0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_019e5049-339b-7e47-8bce-f0e63ecc4bae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_019e5049-339b-7e47-8bce-f0e63ecc4bae" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionGainsAndLossesOnForeignInvestments_019e5049-339b-7b11-9a25-8e8e5da1b466" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionGainsAndLossesOnForeignInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019e5049-339b-71a4-9b53-fe43f842e051" xlink:to="loc_us-gaap_ConversionGainsAndLossesOnForeignInvestments_019e5049-339b-7b11-9a25-8e8e5da1b466" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_jll_JosephLarryQuinlanMember_019e5049-3167-7993-953f-65658262a050" xlink:href="jll-20260630.xsd#jll_JosephLarryQuinlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_jll_JosephLarryQuinlanMember_019e5049-3167-7993-953f-65658262a050" xlink:type="arc" order="2"/>
  </link:definitionLink>
</link:linkbase>
