This list contains acronyms, initialisms, and pseudo-blends that begin with the letter I. For the purposes of this list:
acronym = an abbreviation pronounced as if it were a word, e.g., SARS = severe acute respiratory syndrome, pronounced to rhyme with cars initialism = an abbreviation pronounced wholly or partly using the names of its constituent letters, e.g., CD = compact disc, pronounced cee dee pseudo-blend = an abbreviation whose extra or omitted letters mean that it cannot stand as a true acronym, initialism, or portmanteau (a word formed by combining two or more words). (a) = acronym, e.g.: SARS – (a) severe acute respiratory syndrome (i) = initialism, e.g.: CD – (i) compact disc (p) = pseudo-blend, e.g.: UNIFEM – (p) United Nations Development Fund for Women (s) = symbol (none of the above, representing and pronounced as something else; for example: MHz – megahertz) Some terms are spoken as either acronym or initialism, e.g., VoIP, pronounced both as voyp and V-O-I-P.
(Main list of acronyms)
I – (s) Iodine – One (in Roman numerals)
I0–9 I2C or I-squared-C - (i) Inter-Integrated Circuit I2WD or I2WD – (i) U.S. Intelligence and Information Warfare Directorate (CERDEC)
IA ia – (s) Interlingua language (ISO 639-1 code) IA – (s) Iowa (postal symbol) IAAF – (i) International Association of Athletics Federations ("International Amateur Athletics Federation" from 1912 to 2001; renamed "World Athletics" in 2019) IAAL – (i) I Am A Lawyer IAAS - (p) Infrastructure-as-a-Service IAB – (i) International Association for Biologicals IATA code of McConnell Air Force Base IACREOT – (i) International Association of Clerks, Recorders, Election Officials, and Treasurers IAD – (i) Ion Assisted Deposition IATA code for Washington Dulles International Airport IADS – (i) Integrated Air Defence System IAE - (i) International Aero Engines (aircraft engine joint venture) IAEA – (i) International Atomic Energy Agency IAF {i} Industrial Areas Foundation (i) Israeli Air Force IAFG – (i) Information Assurance Focus Group IAI – (i) International African Institute Israel Aircraft Industries IANA – (i) Internet Assigned Numbers Authority IANAL – (i) I Am Not A Lawyer IAPD International Associates of Paediatric(sic) Dentistry (i) Investment Adviser Public Disclosure iShares Asia Pacific Dividend IAQ – (i) Indoor air quality – Infrequently Asked Questions IAS – (i) Image Assessment System IASIP – (i) It's Always Sunny in Philadelphia IATA – (a/i) International Air Transport Association IATF – International Automotive Task Force IATSE – International Alliance of Theatrical Stage Employees IAU – (i) International Association of Universities – International Astronomical Union IAUC – (i) International Astronomical Union Circular IAW – (i) In Accordance With
IB IB – (i) International Baccalaureate IBA – (i) Important Bird Area IBD – (i) Inflammatory Bowel Disease IBDM – (i) Information Based Decision Making IBDS – (i) Integrated Biological Detection System – International Business Development Specialist IBF - International Boxing Federation IBGe – (i) Isobutylgermane IBGE – (i) Instituto Brasileiro de Geografia e Estatística (Portuguese, "Brazilian Institute of Geography and Statistics") IBHOF - International Boxing Hall of Fame IBM – (i) International Business Machines ibo – (s) Igbo language (ISO 639-2 code) IBRD – (i) International Bank for Reconstruction and Development (part of the World Bank) IBS – (i) Irritable Bowel Syndrome
IC IC (s) Ice Crystals (METAR Code) Iceland (FIPS 10-4 country code) (i) Integrated Circuit - [inner circle] ICANN – (a) Internet Corporation for Assigned Names and Numbers ICAO – (i) International Civil Aviation Organization ICBM – (i) Intercontinental Ballistic Missile ICBM – I see (phonetically "c") BatMan ICBN – (i) International Code of Botanical Nomenclature ICC (i) Integrated Command and Control International Criminal Court International Cricket Council Interstate Commerce Commission International Chamber of Commerce ICD (i) Implantable Cardioverter-Defibrillator Initial Capabilities Document International Classification of Diseases ICE (i/a) (U.S.) Immigration and Customs Enforcement In case of emergency Internal Combustion Engine (Vehicles) ICES – (a/i) International Council for the Exploration of the Sea ICF – (i) Intelligent Community Forum ICHTHYS – (a) Iesous Christos, Theou Yios, Soter (Greek, "Jesus Christ, Son of God, Savior") ICM (i) Improved Conventional Munition Integrated Collection Management International Congress of Mathematicians Iraq Campaign Medal ICMP – (i) Internet Control Message Protocol ICNAF – (i) International Commission for the Northwest Atlantic Fisheries (became NAFO in 1978) ICNI – (i) Integrated Communication, Navigation, and Identification ICO – (i) Intermediate Circular Orbit ICP (i) Inductively coupled plasma Insane Clown Posse ICPE – (a/i) International Conference on Pharmacoepidemiology, the annual conference of the International Society for Pharmacoepidemiology ICRAF – (i) International Centre for Research in Agroforestry (a.k.a. World Agroforestry Centre since 2002) ICRISAT – (i/a) International Crops Research Institute for the Semi-Arid Tropics ICRL – (i) Individual Component Repair List ICRS – (i) International Celestial Reference System ICS (i) In-Country Support Intelligence and Communications Systems Interim Contractor Support ICSI – (p) Intracytoplasmic Sperm Injection ICT – (i) Information and communication technologies ICTH – (i) Island Closest to Heaven/Hell Final Fantasy VIII ICV – (i) Infantry Carrier Vehicle ICW (i) In Co-ordination With Indonesia Corruption Watch Infectious and Chemotherapeutic Waste Insulating Concrete Wall Integral Crystalline Waterproofing (p) Interactive Courseware (i) International Championship Wrestling (defunct US professional wrestling promotion) ICYMI – (i) In Case You Missed It ICZN (i) International Code of Zoological Nomenclature International Commission on Zoological Nomenclature
ID id – (s) Indonesian language (ISO 639-1 code) ID (s) Idaho (postal symbol) (p) Identity (s) Indonesia (FIPS 10-4 country code; ISO 3166 digram) (i) Infantry Division Intelligent Design ID10T Error – (i) Idiot User Error (IT help desk inside joke) IDA (i) U.S. Institute for Defense Analyses International Development Association (part of the World Bank IDC – (i) International Data Corporation "I Don't Care" IDDI – (i) I don't do initialisms (see irony) IDE (i) Integrated Development Environment Integrated Drive Electronics IDeA – (a) Improvement and Development Agency, the former name of Local Government Improvement and Development in the United Kingdom IDEA (a) Individuals with Disabilities Education Act (U.S.) International Data Encryption Algorithm International Design Excellence Awards IDF (i) Israel Defense Forces Intel Development Forum International Dairy Federation IDGAF – (i) I don't give a f**k IDK – (i) I don't know IDKIBTI – I don't know, I'm black, that's it IDL – (i) Interface Definition Language IDN – (s) Indonesia (ISO 3166 trigram) ido – (s) Ido language (ISO 639-2 code) IDR – (s) Indonesian rupiah (ISO 4217 currency code) IDTS – (i) I don't think so
IE i.e. – (i) id est (Latin, roughly "that is") ie – (s) Interlingue language (ISO 639-1 code) IE – (i) Indo-European languages – Internet Explorer – (s) Ireland (ISO 3166 digram) – Iced Earth IEA – (i) International Energy Agency IEC – (i) International Electrotechnical Commission IED – (i) Improvised Explosive Device IEEE – (p) Institute of Electrical and Electronics Engineers ("I triple-E") IELTS – (a) International English Language Testing System IER – (i) Information Exchange Requirement IET – (i) Institution of Engineering and Technology IET – (ii) Initial Entry Training IETF – (i) Internet Engineering Task Force IEW – (i) Intelligence and Electronic Warfare
IF IFAB – (i) International Football Association Board IFAH – (i) International Federation for Animal Health IFAP – (i) International Federation of Agricultural Producers, (i) International Fashion Academy Pakistan IFC – (i) International Finance Corporation (part of the World Bank) – (a) Independent Film Channel IFF – (i) Identification, Friend or Foe – Individually Fresh Frozen – International Flavors and Fragrances IFFN – (i) Identification, Friend, Foe, or Neutral IFO – (i) Identified Flying Object (see also UFO) IFOR – (p) UN Implementation Force – (i) Institute for Operations Research – International Fellowship of Reconciliation IFOV – (i) Instantaneous Field of View IFPI – (i) International Federation of Phonographic Industries IFR – (i) Instrument Flight Rules IFRB – (i) International Frequency Registration Board IFV – (i) Infantry Fighting Vehicle
IG ig – (s) Igbo language (ISO 639-1 code) IG – (i) Inspector General Instagram IGFA – International Game Fish Association IGM - IATA code for Kingman Airport IGNOU – (a) Indira Gandhi National Open University IGS – (i) International Ground Station IGY – (i) Israeli Gay Youth – International Geophysical Year
IH IHÉS – (i) Institut des Hautes Études Scientifiques (French, Institute of Advanced Scientific Studies) IHH – (i) Idiopathic Hypogonadotropic Hypogonadism IHO – (i/a) International Hydrographic Organization IHOP – (i/a) International House of Pancakes, the original name of this American restaurant chain ("EYE-hop") IHR – (i) Institute for Historical Review IHSI – Institutum Historicum Societatis Iesu (Jesuit Historical Institute)
II ii – (s) Sichuan Yi language (ISO 639-1 code) II – (s) Two (in Roman numerals) IIC or I2C - (i) Inter-Integrated Circuit IICA – (i) Inter-American Institute for Cooperation on Agriculture IIE – (i) Innovative Interstellar Explorer iii – (s) Sichuan Yi language (ISO 639-2 code) III – (s) Three (in Roman numerals) IIMSS – If I May Say So IIRC – If I Remember Correctly, If I Recall Correctly IISS – (i) International Institute for Strategic Studies IIT – (i) Illinois Institute of Technology – Indian Institutes of Technology – Indiana Institute of Technology IITM – (i) Image Institute of Technology & Management – Indian Institute of Technology Madras – Indian Institute of Tropical Meteorology I/ITSEC – (a) Interservice/Industry Training, Simulation and Education Conference ("eye-it-sec" or "it-sec")
IJ IJN – (i) Imperial Japanese Navy (World War II) IJWP – (i) Interim Joint Warfare Publication
IK ik – (s) Inupiaq language (ISO 639-1 code) IKEA – (a) Ingvar Kamprad (the company's founder), Elmtaryd (the farm where he was born and raised), Agunnaryd (a village and parish near the farm) iku – (s) (s) Inuktitut language (ISO 639-2 code)
IM IM (s) Isle of Man (FIPS 10-4 territory code) (i) Instant Message (Internet speech) IMA (i) Intermediate Maintenance Activity Institute of Mathematics and Applications IMBD – (i) International Migratory Bird Day IMDb – Internet Movie Database IME - (i) In My Experience IMF (i) id music file/id's music format (audio file format) Impossible Missions Force, the protagonist organization in the Mission: Impossible media franchise International Monetary Fund (the most common use for the initialism) IMHO – (i) In My Humble/Honest Opinion, cf. IMO IMIST AMBO – used to facilitate an informed clinical handover between paramedics, emergency department staff or other healthcare similar to SBAR: Identification, Method of Injury, Index of concern, Signs, Treatment, Allergies, Medication, Background, and Other IML – (i) International Mister Leather IMLAST – (i) International Movement for Leisure Activities in Science and Technology – see MILSET IMNM - (i) - Immune-mediated necrotizing myopathy a rare, but serious ADR of statins [1] IMNSHO – (i) In My Not So Humble Opinion IMO (in my opinion) – (i) In My Opinion, also "imo", cf. IMHO IMPAC – (a) International Merchant Purchase Authorization Card IMPACT – (a) International Medical Products Anti-Counterfeiting Taskforce IMPATT – (p) IMPact Avalanche Transit Time diode IMPT – (i) Institute of Maxillofacial Prosthetists and Technologists IMR – (i) Inzhenernaya Mashina Razgrazhdeniya (Russian Инженерные Машины Разграждения, "Engineer Vehicle Obstacle-Clearing") † IMRI (i) Industrial Membrane Research Institute Information Management Research Institute Institut pour le management de la recherche et de l'innovation (French, "Institute for the Management of Research and Innovation") International Market Research Information Intraoperative Magnetic Resonance Imaging IMRO Internal Macedonian Revolutionary Organization Irish Music Rights Organisation IMRL – (i) Individual Material Readiness List IMS (i) Information Management System International Meat Secretariat Ion Mobility Spectrometer IMSA (i) Illinois Mathematics and Science Academy International Mind Sports Association International Motor Sports Association IMsL – (a) International Ms. Leather IMT – (i) Integrated Management Tool IMU – (i) International Mathematical Union
IN In – (s) Indium IN – (s) India (FIPS 10-4 country code; ISO 3166 digram) – Indiana (postal symbol) – Infantry ina – (s) Interlingua language (ISO 639-2 code) INA – (p) Immigration and Nationality Act INAS – (a) International Near-Earth Asteroid Survey INC – (i) Indian National Congress, one of the national political parties in India (i) Iglesia ni Cristo (Filipino, "Church of Christ") Indian National Congress International Network of Crackers Iraqi National Congress INCITS – (p) InterNational Committee for Information Technology Standards ind – (s) Indonesian language (ISO 639-2 code) IND – (s) India (ISO 3166 trigram) inet – (a) the Internet INDIGO – (p) (U.S.) INtelligence DIvision Gaming Operation INFORMS – (a) (U.S.) Institute for Operations Research and the Management Sciences INFOSEC – (p) Information Security INLA – (i) Irish National Liberation Army INMARSAT – (p) International Maritime Satellite organization INR – (s) Indian rupee (ISO 4217 currency code) INRI – (a/i) Iesus Nazarenus Rex Iudæorum (Latin, "Jesus of Nazareth, King of the Jews") INRIA – (p) Institut national de recherche en informatique et en automatique INS – (i) Immigration and Naturalization Service InSAR – (p) Interferometric synthetic aperture radar INST – (p) Information Standards and Technology in trans. – (p) in transitu (Latin, "in transit") INTSUM – (p) Intelligence Summary INTERFET – (p) International Force for East Timor
IO io – (s) Ido language (ISO 639-1 code) IO – (s) British Indian Ocean Territory (ISO 3166 digram; FIPS 10-4 territory code) IOC (i) Initial Operational Capability Intergovernmental Oceanic Commission International Olympic Committee International Ornithological Congress IOG (formerly IOHK) – Input Output Global. Redirected to Charles Hoskinson IOHK – Input Output Hong Kong. Redirected to Charles Hoskinson IOLTA – (a) Interest on Lawyer Trust Accounts (charitable funding mechanism, especially for legal aid) IOM (i) Iowa, Ohio, Michigan (soybean origin) Institute of Medicine International Organization for Migration Isle of Man IONA – (i) Islands of the North Atlantic (alternate name for Great Britain, Ireland, the Isle of Man, and related islands) IoT - (i) Internet of Things IOT – (s) British Indian Ocean Territory (ISO 3166 trigram) IOT&E – (i) Initial Operational Test and Evaluation IOU – (p) "I Owe You" (Promissory note)
IP IP – (s) Clipperton Island (FIPS 10-4 territory code) (i) Initial Point – Intellectual Property – Internet Protocol IPA – (i) India Pale Ale – International Phonetic Alphabet – Isopropyl alcohol IPB – (i) Intelligence Preparation of the Battlefield IPCC – (i) Intergovernmental Panel on Climate Change Independent Police Complaints Commission ipk – (s) Inupiaq language (ISO 639-2 code) IPL – (i) Inferior Parietal Lobule IPN – (i) Instytut Pamieci Narodowej (Polish, "Institute for National Memory") IPO – (i) Initial public offering IPR – (i) In Progress Review Intellectual Property Rights Intelligence Production Requirement IPT – (i) Integrated Product/Project Team IPTS – (i) Institute for Prospective Technological Studies IPTV – (p) Internet Protocol TeleVision IPW – (i) Interrogation of Prisoners of War
IQ iq – (i) idem quod (Latin, "the same as") IQ – (i) Intelligence Quotient (s) Iraq (ISO 3166 digram) IQD – (s) Iraqi dinar (ISO 4217 currency code)
IR Ir – (s) Iridium IR (i) Infrared Intelligence requirement (military) (s) Iran (FIPS 10-4 country code; ISO 3166 digram) Iran Air (IATA alpha code) see entry for more IRA (i) Individual retirement account (i) Irish Republican Army (any of several armed groups dedicated to Irish republicanism) Internet Research Agency (used in the Mueller report) IRAD – (a) Internal Research and Development IRAN - (I) Inspect and Repair As Necessary IRAS – (p) Infrared Astronomical Satellite IRB – (i) International Rugby Board, a former name of World Rugby IRBM – (i) Intermediate Range Ballistic Missile IRC (i) International Red Cross International reply coupon (i) Internet Relay Chat IREA (i) Intermountain Rural Electric Association (i) International Renewable Energy Alliance (p) Iranian Esperanto Association (i) Internet Radio Equality Act IRGC - (i) Islamic Revolutionary Guard Corps (branch of Iranian Armed Forces IRL (s) Ireland (ISO 3166 trigram) Industrial Research Limited Indy Racing League, former name of the motorsport governing body now known as INDYCAR (i) In real life IRM (i) Illinois Railway Museum Inzhenernaya Razvedyvatelnaya Mashina (Russian Инженерная Разведывательная Машина, "Engineer Reconnaissance Vehicle") † IRN – (s) Iran (ISO 3166 trigram) IRIAF - Islamic Republic of Iran Air Force IRINN - Islamic Republic of Iran News Network IRO – (i) International Refugee Organization IRQ – (s) Iraq (ISO 3166 trigram) IRR – (s) Iranian rial (ISO 4217 currency code) IRS – (i) U.S. Internal Revenue Service IRSN – (i) Institut de radioprotection et de sûreté nucléaire (French, "Institute for Radiation Protection and Nuclear Safety") IRST – (i) Infra-red Search and Track
IS is – (s) Icelandic language (ISO 639-1 code) IS (s) Iceland (ISO 3166 digram) Israel (FIPS 10-4 country code) ISA (i) Individual Savings Account Industry Standard Architecture Instruction Set Architecture International Seabed Authority ISAAA – (i) International Service for the Acquisition of Agri-biotech Applications ISAF (a) International Sailing Federation International Security Assistance Force ISAR – (a) Inverse SAR (Synthetic Aperture Radar) ISB – (i) Intermediate Staging Base ISBN – (i) International Standard Book Number (ISO 2108) ISCCP – (i) International Satellite Cloud Climatology Project ISCII – (a) Indian Standard Code for Information Interchange ISDN – Integrated Services Digital Network ISEF – (a) Intel International Science and Engineering Fair ISEN – (i) Internet Search Environment Number ISF – (i) Internal Security Force ISI Indian Standards Institute, former name of the Bureau of Indian Standards Inter-Services Intelligence (Pakistan) Islamic State of Iraq, an umbrella organization for several Iraqi insurgent groups ISIL – (i/a) Islamic State of Iraq and the Levant ISIS (i/a) Institute for Science and International Security Islamic State of Iraq and Syria ISK – (s) Icelandic krona (ISO 4217 currency code) isl – (s) Icelandic language (ISO 639-2 code) ISL – (s) Iceland (ISO 3166 trigram) ISLN – (i) International Standard Lawyer Number (used initially by LexisNexis Martindale-Hubbell) (i) International School Libraries Network (HQ in Singapore) (s) Isilon Systems, the NASDAQ symbol ISM (i) Industrial, scientific or medical (p) Interstellar medium ISMB – (i) International Society of Matrix Biologists ISMC – (i) Intelligent Sounding Meaningless Conversation ISO (i) In Search Of (s) International Organization for Standardization (from the Greek ίσος, isos, meaning "equal") ISOGP – (i) Indian Society of Orthodontics for General Practitioners [2] ISP (i) International Standardized Profile Internet service provider Information Systems Professional ISPE – (a/i) International Society for Pharmacoepidemiology ISR (i) Intelligence, Surveillance and Reconnaissance (s) Israel (ISO 3166 trigram) ISRO – (i) Indian Space Research Organisation ISS (i) International Shorebird Survey (North America) International Space Station ISSCR – (i) International Society for Stem Cell Research ISSN – (i) International standard serial number (ISO 3297) IST (i) Information System Technology UCF Institute for Simulation and Training ISTAR – (i) Intelligence, Surveillance, Target Acquisition, and Reconnaissance ISTC – (i) Institute of Scientific and Technical Communications (UK) ISTG – (i) I Swear To God ISTS – (i) Intel Science Talent Search ISU (i) Integrated Sight Unit International Skating Union
IT it – (s) Italian language (ISO 639-1 code) IT (i) InferoTemporal (neurophysiology) Information Technology (s) Italy (FIPS 10-4 country code; ISO 3166 digram) ita – (s) Italian language (ISO 639-2 code) ITA – (s) Italy (ISO 3166 trigram) ITAG – (i) Inertial Terrain-Aided Guidance ITALY – (a) I'll Truly Always Love You ITAS – (i) Improved Target Acquisition Sight ITC (i) Incorporated Television Company (defunct British television production company) InferoTemporal Cortex (neurophysiology) ITCZ – (i/p) Intertropical Convergence Zone ITEC – (a) Information Technology Exposition & Conference ITEMS – (a) Interactive Tactical Environment Management System ITER – (a) International Thermonuclear Experimental Reactor ITF – (a) International Tennis Federation ITK – (a) In The Know ITN – (i) Independent Television News (British) ITS (i) Incompatible Time-sharing System Individual Training Standards ITT – (i) International Telephone and Telegraph (U.S.) ITTO – (i) International Tropical Timber Organization ITU (i) Intent-to-Use International Telecommunication Union (International Telegraph Union 1865–1932)
IU iu – (s) (s) Inuktitut language (ISO 639-1 code) IUCN – (i) International Union for the Conservation of Nature and Natural Resources (World Conservation Union) IUD – (i) Intrauterine device (https://www.plannedparenthood.org/learn/birth-control/iud) IUI (i) Indiana University Indianapolis, to be established in 2024 upon the dissolution of Indiana University–Purdue University Indianapolis (IUPUI, below) Intrauterine insemination (http://americanpregnancy.org/infertility/intrauterine-insemination/) IUPAC – (a) International Union of Pure and Applied Chemistry (pronounced "eye-yoo-pac") IUPUI – (a) Indiana University–Purdue University Indianapolis IUSS (i) Integrated Undersea Surveillance System Integrated Unit Simulation System International Union of Soil Sciences
IV IV – (s) Côte d'Ivoire (FIPS 10-4 country code; from Ivory Coast) – Four (in Roman numerals) – (i) IntraVenous (as in intravenous drip or intravenous therapy) IVD – (i) Internet Video Device, intra vas device Iveco – (p) Industrial Vehicles Corporation IVF – (i) In Vitro Fertilisation IVI – (i) Interchangeable Virtual Instrument IVIS – (i/a) Inter-Vehicle Information System IVL – (i) Inter-Visibility Line IVM – (i) In Vitro [Oocyte] Maturation IVO – (i) In Vicinity Of
IW IW – (i) Impact Wrestling IW – (i) Information Warfare IWARS – (p) Infantry Warrior Simulation IWC – (i) International Whaling Commission IWT – (i) Illegal Wildlife Trade IWW – (i) Industrial Workers of the World
IX IX – (s) Nine (in Roman numerals)
IY IY – (s) Saudi–Iraqi neutral zone (FIPS 10-4 territory code; obsolete 1993) Iykyk (acronym) – (i) If You Know You Know
IZ IZ – (s) Iraq (FIPS 10-4 country code)
References