| INESASS | Institute of National Economy - Shanghai Academy of Social Sciences | In English | → Research institutes → Economics |
| INFSB | Institut National de Formation Supérieure du Bâtiment | In French | → Specialized or (poly)technical colleges → Building |
| INGM | Institut National de Génie Mécanique | In French | → Specialized or (poly)technical colleges → Mechanical engineering |
| INHC | Institut National des Hydrocarbures et Chimie | In French | → Specialized or (poly)technical colleges → Chemical technology → Chemistry |
| INI | Institut National d'Informatique | In French | → Specialized or (poly)technical colleges → Computer science |
| INIA | Institut National des Industries Alimentaires | In French | → Specialized or (poly)technical colleges → Beverage industry → Food technology |
| INIM | Institut National des Industries Manufacturières | In French | → Specialized or (poly)technical colleges → 68 |
| INMA | Información y Motivación para el Auto-empleo | In Spanish | → Labour, labour economics |
| INMC | Institut National des Matériaux de Construction | In French | → Specialized or (poly)technical colleges → Building |
| INNORPI | Institut National de la Normalisation et de la Propriété Industrielle | In French | → Standardization → Industrial property |
| INPADOCDB | International Patent Documentation Data Base | In English | → Libraries → Industrial property |
| INPAREL | Institute for the Study of Indo-Pakistan Relations | In English | → International relations |
| INPES | Institut National de Prévention et d’Éducation pour la Santé | In French | → Education → Public health and hygiene |
| INPG | Institut National Polytechnique de Grenoble | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| INPI | Institut National de la Propriété Industrielle | In French | → Industrial property |
| INPL | Institut National Polytechnique de Lorraine (http://ww.inpl-nancy.fr) | In French | → Specialized or (poly)technical colleges |
| INPT | Institut National Polytechnique de Toulouse | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| INPT | Institut National des Postes et Télécommunications | In French | → Specialized or (poly)technical colleges → Telecommunications |
| INSEA | Institut National de Statistique et d'Économie Appliquée | In French | → Specialized or (poly)technical colleges → Economics |
| INSEE | Institut National de la Statistique et des Études Économiques | In French | |
| INSET | Institut National Supérieur de l'Enseignement Technique | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| INSTRAW | (United Nations) International Research and Training Institute for the Advancement of Women | In English | → United Nations → Feminism |
| INTBO | International Network of Transboundary Basin Organizations | In English | → 341224 → Hydrology → 626 → Engineering, technology |
| INTEC | International Netcourse Teacher Enhancement Coalition | In English | → Organizations and associations → Education |
| INTPM | Institut National de Formation de Techniciens Supérieurs des Travaux Publics - Mostganem | In French | → Specialized or (poly)technical colleges → Civil engineering |
| INTPO | Institut National de Formation de Techniciens Supérieurs des Travaux Publics - Ouargla | In French | → Specialized or (poly)technical colleges → Civil engineering |
| IO | Industrial Operations | In English | → 33854 |
| IOC | Indirect Operating Cost | In English | → Prices |
| IOC | Indian Ocean Commission (www.coi-ioc.org) = COI | Commission de l'Océan Indien | In French |
In English | → International relations |
| IOC | Intergovernmental Oceanographic Commission (http://ioc.unesco.org) | In English | → International relations → Marine research, oceanography |
| IOCA | Internacia Organizo pri Civila Aviado = ICAO | International Civil Aviation Organization | In English |
In Esperanto | → International relations → Aeronautics, aircraft → Transport and postal services |
| IOM | International Organization for Migration | In English | → Organizations and associations → Migrations |
| IOMAC | Indian Ocean Marine Affairs Cooperation | In English | → International relations → Marine research, oceanography → Fishing, hunting |
| IOS | Institute of Objective Studies | In English | |
| IOT | Inspraakorgaan Turken (in Nederland) | In Dutch | → Organizations and associations → Migrations |
| IP | Instructor Pilot | In English | → Education → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| IPA | Instrument de Pré-Adhésion | In French | → European Union |
| IPA | Palestinian Investment Promotion Agency | In English | → 33972 |
| IPA | Institute of Public Affairs | In English | → Politics → Public administration, government |
| IPA | Interparlamentarische Arbeitsgemeinschaft | In German | → Associations → Parliaments, representation |
| IPA | International Police Association | In English | → Associations → Police |
| IPAD | Instituto Português de Apoio ao Desenvolvimento | In Portuguese | → Development |
| IPAG | Institut de Préparation à l'Administration Générale | In French | → Public administration, government → Education |
| IPB | International Peace Bureau | In English | → Organizations and associations → Polemology |
| IPB | Instituto Politécnico de Bragança | In Portuguese | → Specialized or (poly)technical colleges |
| IPB | Instituto Politécnico de Beja | In Portuguese | → Specialized or (poly)technical colleges |
| IPC | Institut Polytechnique de Conakry | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| IPC | International Patent Classification | In English | → Industrial property |
| IPCC | International Cooperation Partner Country | In English | → International relations → European Union |
| IPCS | Institute of Peace and Conflict Studies | In English | → Polemology |
| IPI | Istituto per la Promozione Industriale | In Italian | → Industry, industrial policy → Engineering, technology |
| IPIS | Institute for Political and International Studies | In English | → Politics → International relations |
| IPJ | Institut Pratique de Journalisme | In French | → Specialized or (poly)technical colleges → Newspapers, journalism |
| IPKK | Internacia Perfektiga Kurso de Esperanto | In Esperanto | → Education → Artificial languages (linguistics) |
| IPN | Instytut Pamięci Narodowej - Komisja Ścigania Zbrodni przeciwko Narodowi Polskiemu (www.ipn.gov.pl) | In Polish | → Research institutes → Law, jurisprudence → History |
| IPO | International Progress Organization (www.i-p-o.org) | In English | → Organizations and associations → International relations |
| IPO | Initial Public Offering | In English | → Finance |
| IPOS | Intellectual Property Office Singapore | In English | → Industrial property → Artistic property |
| IPPR | Institute for Public Policy Research | In English | → Politics |
| IPR | Internacia Pedagogia Revuo | In Esperanto | → Serial publications, periodicals → Education |
| IPR | Institute of Pacific Relations | In English | → International relations |
| IPR | Intellectual Property Rights | In English | → Industrial property → Artistic property |
| IPRC | International Pacific Research Center | In English | → Research institutes → International relations → Area studies |
| IPRC | Intellectual Property Rights Committee | In English | → Artistic property |
| IPRP | International Preliminary Report on Patentability | In English | → Industrial property |
| IPS | Institute for Policy Science | In English | → Politics |
| IPSA | Institut Polytechnique des Sciences Avancées | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| IPU | Inter-Parliamentary Union | In English | → International relations → Parliaments, representation |
| IQT | Initial Qualification Training | In English | → Education |
| IR | Investor Relations | In English | → Finance |
| IRA | Individual Retirement Account | In English | → Labour, labour economics → Finance |
| IRA | Institut Régional d'Administration | In French | → Public administration, government → Education |
| IRANET | Iranian Research and Academic Network | In English | → Research policy → Education |
| IRAS | Inland Revenue Authority of Singapore | In English | → Public administration, government |
| IRBD | International River Basin District | In English | → 341224 → 626 → 627 |
| IRCANTEC | Institution de Retraite Complémentaire des Agents Non Titulaires de l’État et des Collectivités locales | In French | → Labour, labour economics → Insurance |
| IRCOM | Institut des relations publiques et de la communication | In French | → Higher education, universities → 659 |
| IRD | Inland Revenue Department | In English | → Economics → Central administration |
| IRD | Institut de Recherche pour le Développement | In French | → Development |
| IREM | Institut de Recherches sur l'Enseignement des Mathématiques | In French | → Research institutes → Education → Mathematics |
| IRES | Institut de Recherches Économiques et Sociales | In French | → Research institutes → Economics |
| IRES | Istituto di Ricerche Economiche e Sociali | In Italian | → Economics → Social welfare |
| IRESCO | Institut de Recherche Européen en Sociologie et Socio-économie | In French | → Research institutes → Sociology → Economics |
| IRESCO | Institut de Recherche sur les Sociétés Contemporaines | In French | → Research institutes → Sociology |
| IRG | (Marie Curie) International Reintegration Grants | In English | → Research policy → Labour, labour economics |
| IRIS | Institut des Relations Internationales et Stratégiques (www.iris-france.org) | In English | → Research institutes → International relations |
| IRKS | Institut für Rechts- und Kriminalsoziologie | In German | → Sociology → Law, jurisprudence |
| IRMI | Integrita Retbazita Medio de Informlaborantoj | In Esperanto | → Labour, labour economics |
| IRO | International Refugee Organization = OIR | Organisation Internationale pour les Réfugiés | In French |
In English | → United Nations → Migrations |
| IRPI | Institut de Recherche en Propriété Intellectuelle (www.irpi.ccip.fr) | In French | → Research institutes → Artistic property |
| IRS | Internal Revenue Service | In English | → Public administration, government |
| IRTC | International Rehabilitation Council for Torture | In English | → Organizations and associations → Fundamental rights |
| ISA | International Seabed Authority (www.isa.org.jm) | In English | → Organizations and associations → International relations → Marine research, oceanography → Mining |
| ISA | International Sociological Association | In English | → Associations → Sociology |
| ISA | Invest in Sweden Agency | In English | → 33972 |
| ISA | Institut Supérieur de l'Administration | In French | → Public administration, government → Higher education, universities |
| ISAE | Institut des Sciences Appliquées et Économiques | In French | → Specialized or (poly)technical colleges → Economics |
| ISAE | Institut Supérieur de l'Aéronautique et de l'Espace (www.isae.fr) | In French | → Specialized or (poly)technical colleges → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| ISAF | International Security Assistance Force | In English | → International relations |
| ISAFIS | Indonesian Student Association for International Studies | In English | → Associations → Higher education, universities |
| ISCAE | Institut Supérieur de Commerce et d'Administration des Entreprises | In French | → Management → Higher education, universities |
| ISCAR | International Society for Cultural and Activity Research | In English | → Organizations and associations → Civilization, culture, progress |
| ISCC | Information Systems Coordination Committee = CCSI | Comité de Coordinación de los Sistemas de Información | In Spanish = CCSI | Comité de Coordination des Systèmes d'Information | In French = CCSI | Comitê de Coordenação de Sistemas de Informação | In Portuguese |
In English | → Knowledge management → United Nations |
| ISCED | International Standard Classification of Education | In English | → Standardization → Education |
| ISCO | International Standard Classification of Occupations | In English | → Standardization → Labour, labour economics |
| ISCOM | Institut Supérieur de Communication et Publicité | In French | → Higher education, universities → 659 |
| ISCOS | Istituto Sindacale per la Cooperazione allo Sviluppo | In Italian | → Organizations and associations → Development |
| ISCPA | Institut Supérieur de la Communication, de la Presse et de l'Audiovisuel | In French | → Newspapers, journalism → Higher education, universities → 659 → Arts |
| ISDP | Institute for Security & Development Policy (www.isdp.eu) | In English | → Research institutes → Politics → Development |
| ISDP | Iraq Sustainable Democracy Project (www.iraqdemocracyproject.org) | In English | → Democracy |
| ISDP | Independent Studies Degree Program | In English | → Education |
| ISE | Institut Syndical Européen | In French | → Organizations and associations → Labour, labour economics |
| ISEC | Institute for Social and Economic Change | In English | → Politics → Economics |
| ISEGI | Instituto Superior de Estatística e Gestão de Informação | In Portuguese | → Research institutes → Statistics |
| ISEP | Institut Supérieur d’Électronique de Paris | In French | → Specialized or (poly)technical colleges → Electronics |
| ISER | Institute for Social and Economic Research | In English | → Research institutes → Demography, statistics, sociology → Economics |
| ISESAO | Istituto di Studi Economico-Sociali per l'Asia Orientale | In Italian | → Politics → Economics |
| ISF | Impôt Sur la Fortune | In French | → Taxes, duties |
| ISFC | International Baltic Sea Fishery Commission (www.ibsfc.org) | In English | → International relations → Fishing, hunting |
| ISFOTEG | Institut Supérieur de Formation aux Techniques de Gestion | In French | → Economics → Higher education, universities |
| ISGC | Institut Supérieur de Gestion et de Commerce | In French | → Economics → Higher education, universities |
| ISGSS | Indonesian Studies Graduate Summer School | In English | → Higher education, universities → Area studies |
| ISIAM | Institut Supérieur d'Informatique Appliquée et de Management | In French | → Economics → Higher education, universities |
| ISIC | Institut Supérieur de l'Information et de la Communication | In French | → Economics → Higher education, universities |
| ISIO | Informativno Svetovalna dejavnost v Izobraževanju Odraslih | In Slovenian | → Education |
| ISIR | Institut für Statistik und internationale Registrierungen | In German | → Research institutes → Statistics |
| ISIS | International Society of Infant Studies | In English | → Organizations and associations → Education → Pediatry |
| ISIS | (Malaysia) Institute of Strategic and International Studies | In English | → International relations |
| ISIS | Institute of Security and International Studies | In English | → International relations → Polemology |
| ISL | Institut de Sondages Lavialle | In French | → Statistics |
| ISM | Institut Supérieur Maritime | In French | → Specialized or (poly)technical colleges → Marine research, oceanography → 627 → Vehicle engineering |
| ISME | Irish Small and Medium Enterprises | In English | → Organizations and associations → Economic policy |
| ISMP | Institut Supérieur de Management Public | In French | → Management → Public administration, government |
| ISNHB | Institut des Sciences de la Nature - Université des Sciences et de la Technologie Haouari Boumediene | In French | → Higher education, universities |
| ISP | Instytut Studiów Politycznych | In Polish | → Research institutes → Politics |
| ISPA | Instrument Structurel de Préadhésion | In French | → International relations → European Union |
| ISPI | Istituto di Studi di Politica Internazionale | In Italian | → International relations |
| ISR | International Search Report | In English | → Industrial property |
| ISS | Institute for Strategic Studies | In English | → International relations |
| ISS | Institute of Social Studies | In English | → Organizations and associations → Sociology |
| ISSP | (Sun Yat-Sen) Institute for Social Sciences and Philosophy | In English | → Philosophy, psychology |
| ISST | Institute of Social Studies Trust | In English | → Sociology |
| ISST | Institut de Santé et de Sécurité au Travail | In French | → Labour, labour economics → Medicine |
| ISST | Institut des Sciences Sociales du Travail | In French | → Labour, labour economics → Sociology |
| ISTA | Institut Supérieur Textile d'Alsace | In French | → Specialized or (poly)technical colleges → Textile industry |
| ISTA | Institut Supérieur de Technologie d'Antananarivo | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ISTAB | Institut Supérieur des Techniques Appliquées d'Ébonda | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ISTAK | Institut Supérieur des Techniques Appliquées de Kinshasa | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ISTAT | Istituto nazionale di statistica | In Italian | → Statistics |
| ISTC | Institut des Stratégies et Techniques de Communication | In French | → Higher education, universities → 659 |
| ISTCS | Institut Supérieur de Technologie Chimique de Sofia | In French | → Specialized or (poly)technical colleges → Chemical technology |
| ISTG | Institut Supérieur Technique de Gabé | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ISTG | Institut Supérieur Technique de Gabés | In French | → Higher education, universities |
| ISTHB | Institut des Sciences de la Terre - Université des Sciences et de la Technologie Haouari Boumediene | In French | → Higher education, universities → Earth sciences |
| ISTIA | Institut des Sciences et Techniques de l'Ingénieur d'Angers | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ISTIM | Institut Supérieur Technologique des Industries et des Mines de Gafsa | In French | → Specialized or (poly)technical colleges → Mining |
| ISTK | Institut Supérieur du Textile de Ksar Hellal | In French | → Specialized or (poly)technical colleges → Textile industry |
| ISTK | Internacia Studumo pri Turismo kaj Kulturo | In Esperanto | → Tourism → Specialized or (poly)technical colleges → Civilization, culture, progress |
| ISTM | International Society of Travel Medicine | In English | → Tourism → Medicine |
| ISTN | Institut Supérieur de Technologie de Nabeul | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ISTS | Institut Supérieur de Technologie d'Antsiranana | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ISU | International Space University | In English | → Higher education, universities → Astronomy |
| ISV | Independent Software Vendor | In English | → Software → Trade |
| ITA | Ingénieurs, Techniciens, Administratifs | In French | → Labour, labour economics → Engineering, technology |
| iTACITUS | Intelligent Tourism And Cultural Information Through Ubiquitous Services | In English | → Networks, communication → Civilization, culture, progress → Tourism |
| ITAF | Institut des Techniques Administratives et Financières | In French | → Economics → Finance → Accounting |
| ITC | Institut de Technologie du Cambodge | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| ITCHKSAR | Innovation and Technology Commission Hong Kong Special Administrative Region | In English | → Industry, industrial policy → Engineering, technology |
| ITECH | Institut Textile et Chimique | In French | → Specialized or (poly)technical colleges → Chemical technology → Leather industry → Textile industry |
| ITEdu | IEEE (Institute of Electrical and Electronics Engineers) Transactions on Education | In English | → Serial publications, periodicals → Education → Electrical engineering |
| ITeR | Informatietechnologie en Recht | In Dutch | → Computer science → Law, jurisprudence |
| ITF | Institut de Technologie du Froid | In French | → Specialized or (poly)technical colleges |
| ITFC | International Islamic Trade Finance Corporation | In English | → Finance → International economic cooperation |
| ITLOS | International Tribunal for the Law of the Sea (www.itlos.org) | In English | → International law → United Nations |
| ITO | International Trade Organization | In English | → Organizations and associations → Trade → International economic cooperation |
| ITP | Integrated Training Plan | In English | → Education |
| ITPE | Ingénieur des Travaux Publics de l'État | In French | → Central administration → Civil engineering |
| ITPO | Investment and Technology Promotion Office | In English | → Economics → Engineering, technology |
| ITT | Information Technology and Tourism | In English | → Serial publications, periodicals → Tourism |
| ITUC | Interregional Trade Union Council | In English | → Organizations and associations → Labour, labour economics |
| ITUH | International Trade Union House | In English | → Organizations and associations → Labour, labour economics |
| IUFM | Institut Universitaire de Formations des Maîtres | In French | → Education |
| IUHR | Inter-African Union of Human Rights (www.iuhr.org) = UIDH | Union Interafricaine des Droits de l'Homme | In French |
In English | → International relations → Fundamental rights |
| IULO | International Union of Local Authorities | In English | → Organizations and associations → Municipal administration |
| IUOTO | International Union of Official Travel Organisations | In English | → Organizations and associations → Tourism |
| IUOTPO | International Union of Official Tourist Publicity Organizations | In English | → Organizations and associations → Tourism |
| IUP | Institut Universitaire Professionnalisé | In French | → Specialized or (poly)technical colleges → Higher education, universities |
| IUP | Inter-University Program for Chinese Language Studies | In English | → Higher education, universities → Language, linguistics, literature |
| IUSCT | Iran-United States Claims Tribunal | In English | → International law |
| IUT | Institut Universitaire de Technologie | In French | → Higher education, universities → Engineering, technology |
| IV | Industriellenvereinigung (www.iv-net.at) | In German | → Organizations and associations → Industry, industrial policy |
| IVA | Imposta sul Valore Aggiunto = TVA | Taxe sur la Valeur Ajoutée | In French = BTW | Belasting op Toegevoegde Waarde | In Afrikaans = IVA | Impost sobre el valor afegit | In Catalan = PDV | Porez na dodatu vrijednost | In Bosnian = ДДС | Данъкът върху добавената стойност | In Bulgarian = VAT | Value Added Tax | In English = AVI | Aldonvalora imposto | In Esperanto = ΦΠΑ | Φόρος Προστιθέμενης Αξίας | In Greek = DPH | Daň z přidané hodnoty | In Czech = Moms | Meromsætningsafgift | In Danish = IVA | Impuesto al Valor Agregado | In Spanish = MwSt | Mehrwertsteuer | In German = BTW | Belasting over de Toegevoegde Waarde | In Dutch = MVA | Merverdiavgift | In Norwegian = PVM | Pridėtinės vertės mokestis | In Lithuanian = VASK | Virðisaukaskattur | In Icelandic = PPN | Pajak Pertambahan Nilai | In Indonesian = Áfa | Általános forgalmi adó | In Hungarian = PDV | Porez na dodanu vrijednost | In Croatian = ALV | Arvonlisävero | In Finnish = מע"מ | מס ערך מוסף | In Hebrew = KDV | Katma Değer Vergisi | In Turkish = VAT | ภาษีมูลค่าเพิ่ม | In Thai = VAT | மதிப்புக் கூட்டு வரி | In Tamil = DPH | Daň z pridanej hodnoty | In Slovak = НДС | Налог на добавленную стоимость | In Russian = TVA | Taxa pe valoarea adăugată | In Romanian = IVA | Imposto sobre o Valor Acrescentado | In Portuguese = VAT | 增值税 | In Chinese |
In Italian | → Taxes, duties |
| IVA | Impost sobre el valor afegit = TVA, BTW, PDV, ДДС, VAT, AVI, ΦΠΑ, DPH, Moms, MwSt, MVA, PVM, VASK, PPN, Áfa, ALV, מע"מ, KDV, НДС (look above) |
In Catalan | → Taxes, duties |
| IVA | Impuesto al Valor Agregado = TVA, BTW, PDV, ДДС, VAT, AVI, ΦΠΑ, DPH, Moms, MwSt, MVA, PVM, VASK, PPN, Áfa, ALV, מע"מ, KDV, НДС (look above) |
In Spanish | → Taxes, duties |
| IVA | Imposto sobre o Valor Acrescentado = TVA, BTW, PDV, ДДС, VAT, AVI, ΦΠΑ, DPH, Moms, MwSt, MVA, PVM, VASK, PPN, Áfa, ALV, מע"מ, KDV, НДС (look above) |
In Portuguese | → Taxes, duties |
| IVRIS | Institut pro výzkum reprodukce a integrace společnosti | In Czech | → Sociology |
| IWBC | International Boundary and Water Commission = CILA | Comisión Internacional de Límites y Agua | In Spanish = CILA | Comissão Internacional sobre Limites e Água | In Portuguese |
In English | → International relations |
| IWC | International Whaling Commission | In English | → Organizations and associations → International relations → Fishing, hunting |
| IWEP | Institute of World Economics and Politics | In English | → International relations → Economics |
| IWI | Industriewissenschaftliches Institut | In German | → Research institutes → Industry, industrial policy → Engineering, technology |