– (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 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