| IAPU | Improved Auxiliary Power Unit | In English | → Electrical engineering |
| IARC | International Agency for Research on Cancer | In English | → Organizations and associations → Oncology |
| IAS | Identification, Authentification et Signature | In French | → Computer science → Telecommunications |
| IAS | Identifizierung, Authentifizierung, Signierung | In German | → Telecommunications |
| IAS | Interface d'Authentification Serveur | In French | → Networks, communication → Telecommunications |
| IAS | Integrated Avionics Subsystem | In English | → Aeronautics, aircraft |
| IAS | Institute of Aeronautical Sciences | In English | → Aeronautics, aircraft |
| IAS | International Accounting Standards | In English | → Standardization → Commercial law → Accounting |
| IASB | International Accounting Standards Board | In English | → Standardization → Commercial law → Accounting |
| IASCF | International Accounting Standards Committee Foundation | In English | → Foundations → Standardization → Commercial law |
| IASTAM | International Association for the Study of Traditional Asian Medicine | In English | → Associations → 6158 |
| IAT | Integrated Avionics Test | In English | → Aeronautics, aircraft |
| IATA | International Air Transport Association | In English | → Associations → Transport and postal services |
| IATSS | International Association of Traffic and Safety Sciences | In English | → Associations → Transport and postal services |
| IAURIF | Institut d'Aménagement et d'Urbanisme de la Région Île-de-France | In French | → Transport and postal services → Regional planning |
| IAVI | International AIDS Vaccine Initiative | In English | → Immunology and allergy → Infectious diseases |
| IB | Institut für Bodenforschung (www.boku.ac.at/boden/) | In German | → Research institutes → Agricultural sciences |
| IBA | Institute for Biomedical Aging Research | In English | → Research institutes → Biological sciences → Medicine |
| IBA | Israel Broadcasting Authority (www.iba.org.il) | In English | → Telecommunications |
| IBB | Institut für Betonbau | In German | → Building |
| IBB | International Broadcasting Bureau | In English | → Telecommunications |
| IBBA | Istituto di Biologia e Biotecnologia Agraria: Sezione di Pisa | In Italian | → Biological sciences → Biotechnology |
| IBC | International Bioethics Committee | In English | → Ethics → Biotechnology → Medicine |
| IBD | Inflammatory Bowel Disease | In English | → Immunology and allergy → Pathology |
| IBE | International Bureau for Epilepsy (www.ibe-epilepsy.org) | In English | → Organizations and associations → Neurology |
| IBEB | Instituto de Biofísica e Engenharia Biomédica | In Portuguese | → Biochemistry, biophysics → Biotechnology → Medicine |
| IBEW | International Brotherhood of Electrical Workers | In English | → Organizations and associations → Electrical engineering |
| IBF | Institut für Bauschadensforschung | In German | → Building |
| IBICT | Instituto Brasileiro de Informação em Ciência e Tecnologia | In Portuguese | → Mathematics and natural sciences |
| IBN | Institut für Biophysik und Nanosystemforschung | In German | → Biochemistry, biophysics → Biotechnology |
| IBN | Institute of Bioengineering and Nanotechnology | In English | → Research institutes → Biotechnology |
| IBO | Österreichisches Institut für Baubiologie und -ökologie | In German | → Building |
| IBRI | Icelandic Building Research Institute | In English | → Building |
| IBS | Irritable Bowel Syndrome | In English | → Pathology |
| IBT | Internationaler Bund der Tierversuchsgegner (www.tierversuchsgegner.at) | In German | → Organizations and associations → Nature → Pharmacology, toxicology |
| IC | Intercommunications | In English | → Networks, communication → Telecommunications |
| IC | Internal Combustion | In English | → Mechanical engineering |
| IC | Integrated Circuit | In English | → Electronics |
| IC/ES | Intercommunication/Emergency Station | In English | → Telecommunications |
| ICA | Institut de Chimie de Annaba | In French | → Specialized or (poly)technical colleges → Chemical technology → Chemistry |
| ICA | Internal Carotid Artery | In English | → Anatomy |
| ICA | Ingénieur du Contrôle Aérien | In French | → Aeronautics, aircraft → Transport and postal services |
| ICAAC | Interscience Conference on Antimicrobial Agents and Chemotherapy | In English | → Medicine |
| ICAD | International Conference on Alzheimer's Disease (and Related Disorders) | In English | → Congresses → Neurology |
| ICAD | International Conference on Auditory Display | In English | → Congresses → Human-computer interaction → Telecommunications |
| ICADTS | International Council on Alcohol and Traffic Safety | In French | → Organizations and associations → Medicine → Transport and postal services |
| ICAE | Integrated Computer-Aided Engineering | In English | → Serial publications, periodicals → Computer-based techniques → Engineering, technology |
| ICAITI | Instituto Centroamericano de Investigación y Tecnología | In Spanish | → Research institutes → Research policy → Engineering, technology |
| ICALIN | Indicateur composite des activités de lutte contre les infections nosocomiales | In French | → Infectious diseases |
| ICAM | Integrated Computer-Aided Manufacturing | In English | → Computer-based techniques → Engineering, technology |
| ICAM | Institut Catholique d'Arts et Métiers | In French | → Roman catholic church → Specialized or (poly)technical colleges → Engineering, technology |
| ICAO | International Civil Aviation Organization = IOCA | Internacia Organizo pri Civila Aviado | In Esperanto |
In English | → Organizations and associations → Aeronautics, aircraft → Transport and postal services |
| ICAOB | ICAO Bulletin (International Civil Aviation Organization) | In English | → Serial publications, periodicals → Aeronautics, aircraft → Transport and postal services |
| ICAR | Indian Council of Agricultural Research | In English | → Agricultural sciences |
| ICAR | Incubateur de Champagne-Ardenne (www.icar-incubateur.fr) | In French | → Engineering, technology |
| ICARDA | International Center for Agricultural Research in the Dry Areas | In English | → Research institutes → Agricultural sciences |
| ICARE | Instrumentation, Commande et Architecture des Robots Évolués | In French | → Electronics |
| ICB | International Centre of Biocybernetics | In English | → Research institutes → Computer science → Electronics |
| ICBM | Intercontinental Ballistic Missile | In English | → Military engineering |
| ICC | Integrated Circuit(s) Cards | In English | → Electronics |
| ICC | International Association for Cereal Science and Technology | In English | → Associations → Agricultural sciences |
| ICCAT | International Commission for the Conservation of Atlantic Tunas (www.iccat.es) | In English | → Nature → Fishing, hunting |
| ICCF | Institutul Naţional de Cercetare-Dezvoltare Chimico-Farmaceutică | In Romanian | → Chemistry → Pharmacology, toxicology → Chemical technology |
| ICD-O | International Classification of Diseases for Oncology | In English | → Bibliography → Oncology |
| ICE | Ideal Cabin Environment | In English | → Aeronautics, aircraft |
| ICF | International Coach Federation (www.coachfederation.org) | In English | → Organizations and associations → 659 |
| ICF | Intracellular fluid | In English | → Physiology |
| ICG | In-Flight Coverall Garment | In English | → Aeronautics, aircraft → Spaceflight engineering, astronautics |
| ICH | International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use | In English | → Pharmacology, toxicology → Veterinary medicine |
| ICID | International Commission on Irrigation and Drainage | In English | → Organizations and associations → Agricultural sciences → Environmental technology, water supply, waste management |
| ICID | International Commission for Irrigation and Drainage = CIID | Commission Internationale pour les Irrigations et le Drainage | In French |
In English | → Organizations and associations → 627 → Agricultural sciences |
| ICIE | Institute for Communications and Information Engineering | In English | → Telecommunications → Computer science |
| ICiSM | IEEE (Institute of Electrical and Electronics Engineers) Circuits Systems Magazine | In English | → Serial publications, periodicals → Electronics |
| ICLARM | International Centre for Living Aquatic Resources Management | In English | → Fishing, hunting |
| ICLC | Interlab Cell Line Collection (www.iclc.it) | In English | → Cytology → Biotechnology |
| ICLD | Interlab Cell Line Database | In English | → Cytology → Biotechnology |
| ICMAB | Instituto de Ciencia de Materiales de Barcelona | In Spanish | → 620 |
| ICME | Institute of Cast Metals Engineers | In English | → Metallurgy |
| ICMI | Inductive Components Manufacturing Inc. (www.icmiinc.com) | In English | → Electrical engineering |
| ICMJE | International Committee of Medical Journal Editors (www.icmje.org) | In English | → Serial publications, periodicals → Medicine |
| ICMR | Indian Council for Medical Research | In English | → Medicine |
| ICMS | Ingénierie et Contrôle des Matériaux et des Structures | In French | → 620 → Mechanical engineering |
| ICN | International Conference on Nutrition = CIN | Conferencia Internacional sobre Nutrición | In Spanish = CIN | Conférence Internationale sur la Nutrition | In French = CIN | Conferência Internacional sobre Nutrição | In Portuguese |
In English | → Congresses → Nutrition |
| ICN | Inspectorate of Civil Navigation | In English | → Public administration, government → Transport and postal services |
| ICOLD | International Commission on Large Dams (www.icold-cigb.org) | In English | → Organizations and associations → 627 |
| IComM | IEEE (Institute of Electrical and Electronics Engineers) Communications Magazine | In English | → Serial publications, periodicals → Networks, communication → Telecommunications |
| ICORD | International Collaboration on Repair Discoveries | In English | → Organizations and associations → Neurology → Traumatology |
| ICOS | Integrated Cargo Operating Software | In English | → Software → Transport and postal services |
| ICOS | Integrated Communications Organizing Standard | In English | → Standardization → Telecommunications |
| ICOUR | Irrigation Company for the Upper Regions | In English | → 627 → Agricultural sciences |
| ICP | Intracranial pressure | In English | → Physiology → Neurology |
| ICP | Instituto de Catálisis y Petroleoquímica | In Spanish | → Chemical technology → 665 |
| ICPDR | International Commission for the Protection of the Danube River | In English | → Organizations and associations → Nature and society → 627 |
| ICPO | Institute of Cytology & Preventive Oncology | In English | → Research institutes → Cytology → Oncology |
| ICPS | International Conference on the Physics of Semiconductors | In English | → Congresses → Electricity, magnetism, electromagnetism → 539 → Electrical engineering |
| ICR | Inductance, Capacitance, and Resistance | In English | → Physics → Electrical engineering |
| ICRAT | International Conference on Research in Air Transportation | In English | → Congresses → Transport and postal services |
| ICRC | 적십자 국제 위원회 (www.icrc.org) = CICR | Comité Internacional de la Cruz Roja | In Spanish = ICRC | International Committee of the Red Cross | In English = CICR | Comité International de la Croix-Rouge | In French = CICV | Comitê Internacional da Cruz Vermelha | In Portuguese = МККК | Международный комитет Красного Креста | In Russian = SSKK | Starptautiskā Sarkanā Krusta Komiteja | In Latvian = CICR | Comitato Internazionale della Croce Rossa | In Italian = CICR | Comitè Internacional de la Creu Roja | In Catalan = CICR | Comitât entèrnacionâl de la Crouèx-Roge | FRP |
In Korean | → Organizations and associations → Medicine |
| ICRC | International Committee of the Red Cross (www.icrc.org) = CICR, CICV, МККК, SSKK (look above) |
In English | → Organizations and associations → Medicine |
| ICRISAT | International Crops Research Institute for the Semi-Arid Tropics | In English | → Organizations and associations → Agricultural sciences |
| ICRP | International Commission on Radiological Protection | In English | → Nuclear technology |
| ICRU | International Commission on Radiation Units and Measurements = CIUMR | Comisión Internacional de Unidades y Medidas Radiológicas | In Spanish = CIUMR | Commission Internationale des Unités et des Mesures de Radiation | In French = CIUMR | Comissão Internacional de Unidades e Medidas Radiação | In Portuguese |
In English | → Standardization → Nuclear technology |
| ICS | Interphone Control Station | In English | → Telecommunications |
| ICS | Intercommunication System | In English | → Networks, communication → Telecommunications |
| ICS | Intelligent Control Systems | In English | → Engineering, technology |
| ICSE | Impact of Computing in Science and Engineering | In English | → Serial publications, periodicals → Computer science → Mathematics and natural sciences → Engineering, technology |
| ICSI | Injection Intracytoplasmique du Spermatozoïde | In French | → Gynaecology |
| ICSI | Institutul Naţional de Cercetare-Dezvoltare pentru Tehnologii Criogenice şi Izotopice | In Romanian | → Physics |
| ICSTI | International Council for Scientific and Technical Information | In English | → Libraries → Mathematics and natural sciences → Engineering, technology |
| ICT | Information and Communications Technology = TIC | Tecnologías de la Información y la Comunicación | In Spanish = IKT | Informations- und Kommunikationstechnologie | In German = TIC | Technologies de l'Information et de la Communication | In French = IKT | Informations- og kommunikationsteknologi | In Danish = IKT | Inligtings- en kommunikasietegnologie | In Afrikaans = ICT | Informatie- en Communicatietechnologie | In Dutch = TMK | Teknologi Maklumat dan Komunikasi | In Malay |
In English | → Computer science → Telecommunications |
| ICT | Informatie- en Communicatietechnologie = TIC, IKT, TMK (look above) |
In Dutch | → Computer science → Telecommunications |
| ICTA | Instituts et Centres Techniques Agricoles | In French | → Research institutes → Agricultural sciences |
| ICTAF | Interdisciplinary Center for Technological Analysis & Forecast | In English | → Energy economics |
| ICTAF | Interdisciplinary Center for Technology Analysis & Forecasting | In English | → Engineering, technology |
| ICU | Intensive Care Unit | In English | → Medicine |
| ICU | Intersection Capacity Utilization | In English | → Transport and postal services |
| ICV | Institut Cardiovasculaire | In French | → Cardiology |
| IDA | Irrigation Development Authority | In English | → 627 → Agricultural sciences |
| IDA | Integrated Display Assembly | In English | → Human-computer interaction → Electronics |
| IDAE | Instituto para la Diversificación y Ahorro de la Energía | In Spanish | → Energy economics |
| IDATE | Institut de l'Audiovisuel et des Télécommunications en Europe | In French | → Cinema, movies → Telecommunications |
| IDB | In-Suit Drink Bag | In English | → Spaceflight engineering, astronautics → Beverage industry |
| IDDM | Insulin-Dependent Diabetes Mellitus = DID | Diabète insulino-dépendant | In French = DMID | Diabetes mellitus insulino-dependente | In Portuguese = DMID | Diabetes mellitus insulino-dependiente | In Spanish |
In English | → Physiology → Pathology |
| IDE | Interactive Development Environment | In English | → Software → 6585 |
| IDE | Integrated Design Environment | In English | → 6585 |
| IDE | Initial Design Evaluation | In English | → 6585 |
| IDEA | Inventer la Distribution Électrique de l'Avenir | In French | → Electrical engineering |
| IDEAS | Initial Design and Evaluation Analysis System | In English | → 6585 |
| IDEAS2 | Independent Design and Evaluation of Advanced Spacecraft | In English | → Spaceflight engineering, astronautics → 6585 |
| IDÉE | Institut Des Épilepsies de l‘Enfant et de l‘Adolescent | In French | → Neurology → Pediatry |
| IDEG | Integratie van Duurzame Energie-toepassingen in Gebouwen | In Dutch | → Building |
| IDEM | Informations- und Dokumentationsstelle Ethik in der Medizin | In German | → Libraries → Ethics → Medicine |
| IDEMM | Ingénierie Documentaire, Édition et Médiation Multimédia | In French | → Document processing → Libraries → Graphic industries, printing, publishing |
| IDF | International Diabetes Federation (www.idf.org) = FID | Fédération Internationale du Diabète | In French = FID | Federación Internacional de Diabetes | In Spanish |
In English | → Organizations and associations → Pathology |
| IDF | International Dairy Federation | In English | → Organizations and associations → Agricultural sciences → Food technology |
| IDIOM | Information Diffusion across Interactive Online Media | In English | → 007 → Newspapers, journalism → Telecommunications |
| IDITE | Instituto de Desenvolvimento e Inocaçao Tecnológica | In Portuguese | → Engineering, technology |
| IDM | Immuno-Designed Molecules | In English | → Biotechnology |
| IDN | Institut Industriel du Nord | In French | → Specialized or (poly)technical colleges → Engineering, technology |
| IDR | Initial Design Review | In English | → 6585 |
| IDR | Intermediate Design Review | In English | → 6585 |
| IDR | Interim Design Review | In English | → 6585 |
| IDS | Integrated Design Support | In English | → 6585 |
| IDS | Integrated Design System | In English | → 6585 |
| IDS | Integrated Defense Simulator | In English | → Military engineering |
| IDSNET | Integrated Defense System Network | In English | → 355 → Military engineering → Networks, communication |
| IDSNET | Integrated Defense Simulator Network | In English | → Military engineering → Networks, communication |
| IDSR | Initial Design Status Review | In English | → 6585 |
| IDsW | InformatieDesk standaarden Water | In Dutch | → Environmental technology, water supply, waste management |
| IDTA | Interdivisional Technical Agreement | In English | → Engineering, technology |
| IE | Ion-Etching | In English | → Engineering, technology |
| IEA | Integrated Electronic Assembly | In English | → Electronics |
| IEA | Ingénieur de l’Électronique Aéronautique | In French | → Electronics → Aeronautics, aircraft → Transport and postal services |
| IEA | 国際エネルギー機関 = AIE | Agence Internationale de l'Énergie | In French = IEA | International Energy Agency | In English = IEA | Internationale Energieagentur | In German = МЭА | Международное энергетическое агентство | In Russian = MAE | Międzynarodowa Agencja Energii[edytuj] | In Polish = IEA | Internationaal Energie Agentschap | In Dutch = AIE | Agencia Internacional de la Energía | In Spanish |
In Japanese | → International relations → Energy economics |
| IEA | International Energy Agency = AIE, МЭА, MAE (look above) |
In English | → International relations → Energy economics |
| IEA | Internationale Energieagentur = AIE, МЭА, MAE (look above) |
In German | → International relations → Energy economics |
| IEA | Internationaal Energie Agentschap = AIE, МЭА, MAE (look above) |
In Dutch | → International relations → Energy economics |
| IEA | Institutul de Economie Agrara | In Romanian | → Economics → Agricultural sciences |
| IEB | Instituto de Engenharia Biomédica | In Portuguese | → Biotechnology → Medicine |
| IEC | International Electrotechnical Commission = CEI | Comisión Electrotécnica Internacional | In Spanish = CEI | Commission Électrotechnique Internationale | In French = CEI | Comissão Eletrotécnica Internacional | In Portuguese |
In English | → Electrical engineering |
| IECCAB | IEC (International Electrotechnical Commission) Conformity Assessment Board | In English | → Electrical engineering |
| IECO | Inboard Engine Cutoff | In English | → Mechanical engineering |
| IED | Innovation Énergie Développement | In French | → Energy economics |
| IEDL | IEEE (Institute of Electrical and Electronics Engineers) Electron Device Letters | In English | → Serial publications, periodicals → Electronics |
| IEDR | Ireland's Domain Registry | In English | → Networks, communication → Telecommunications |
| IEE | Intelligente Energie Europa = IEE | Intelligent Energy Europe | In English |
In German | → Energy economics |
| IEE | Intelligent Energy Europe = (look above) |
In English | → Energy economics |
| IEE | Institut für Elektrische Energietechnik | In German | → Electrical engineering |
| IEE | Institut für Grundlagen der Elektrotechnik und Elektronik | In German | → Electrical engineering → Electronics |
| IEE | Institution of Electrical Engineers | In English | → Electrical engineering |
| IEE | International Electronics & Engineering | In English | → Electronics |
| IEEE | Institute of Electrical and Electronic(s) Engineers | In English | → Electrical engineering → Electronics |
| IEEEN | IEEE (Institute of Electrical and Electronics Engineers) Network | In English | → Serial publications, periodicals → Computer science → Telecommunications |
| IEEEP | IEEE (Institute of Electrical and Electronics Engineers) Proceedings | In English | → Serial publications, periodicals → Electrical engineering |
| IEEES | IEEE (Institute of Electrical and Electronics Engineers) Spectrum | In English | → Serial publications, periodicals → Electrical engineering |
| IEEP | Institution of Electrical Engineers Proceedings | In English | → Serial publications, periodicals → Electrical engineering |
| IEF | International Energy Foundation | In English | → Foundations → Energy economics |
| IEKA | Internacia Esperanto-Klubo Aŭtomobilista | In Esperanto | → Organizations and associations → Vehicle engineering → Transport and postal services |
| IEMC | Intrasystem Electromagnetic Compatibility | In English | → Electrical engineering |
| IEMCAP | Intrasystem Electromagnetic Compatibility Computer Analysis Program | In English | → Computer-based techniques → Electrical engineering |
| IEMN | ÉInstitut d'Électronique, de Microélectronique et de Nanotechnologie | In French | → Electronics |
| IEMN | Institut d'Électronique et de Microélectronique du Nord | In French | → Electronics |
| IEMW | Institut für Industrielle Elektronik und Materialwissenschaften | In German | → 620 → Electronics |
| IER | Internationale Elektronische Rundschau | In German | → Serial publications, periodicals → Electronics |
| IER | Institute of Energy Economics and the Rational Use of Energy | In English | → Energy economics |
| IEREJ | Institution of Electronic Radio Engineers Journal | In English | → Serial publications, periodicals → Electronics → Telecommunications |
| IES | Information und Einsatz im Sanitätsdienst | In German | → Medicine |
| IESD | Instrumentation and Electronic Systems Division | In English | → Electronics |
| IESD | Institute of Energy and Sustainable Development | In English | → Energy economics |
| IESNA | Illuminating Engineering Society of North America | In English | |
| IET | Institution of Engineering and Technology | In English | → Engineering, technology |
| IET | Institut Européen de Technologie | In French | → Engineering, technology |
| IET | International Emissions Trading | In English | → Environmental technology, water supply, waste management |
| IETCC | Instituto Eduardo Torroja de Ciencias de Construcción | In Spanish | → Civil engineering → Building |
| IETDL | IET (Institution of Engineering and Technology) Digital Library | In English | → Libraries → Engineering, technology |
| IETE | Institution of Electronics Telecommunication Engineers | In English | → Serial publications, periodicals → Electronics → Telecommunications |
| IETS | Interim European Telecommunications Standard | In English | → Standardization → Telecommunications |
| İETT | İstanbul Elektrik Tramvay ve Tünel | In Turkish | → Electrical engineering → Transport and postal services |
| IExp | IEEE (Institute of Electrical and Electronics Engineers) Expert | In English | → Serial publications, periodicals → Electrical engineering |
| IF | Intermediate Frequency | In English | → Telecommunications |