Isa may refer to:
ISA is a three-letter acronym that may stand for:
- Instrument Society of America, now called the Instrumentation, Systems, and Automation Society, is a non-profit technical society for engineers, technicians, businessmen, educators and students, who work, study or are interested in industrial automation and pursuits related to it.
- Isosaccharinic acid, a product of degradation of cellulose at high pH, strongly complexing some actinides in radioactive waste conditioned in cement.
- Industry Standard Architecture, a now-obsolete I/O bus standard for IBM-compatible PC motherboards.
- Instruction Set Architecture, the complete specification of the interface between computer programs that have been written and the underlying computer hardware that carries out the actual work.
- Information Security Architecture, a buzzword variant for information security.
- ISA platform ("NOS"), an operating system software for Nokia mobile telephones.
- Microsoft Internet Security and Acceleration Server, a Microsoft server product.
- Instrumentation, Systems, and Automation Society, formerly the Instrument Society of America, a professional organization for instrument engineers.
- Isa (computer science), a relationship between objects; for instance, an apple tree "is a" tree.
In aviation and space exploration:
- International Standard Atmosphere, a tabulation with altitude of the standard variation of pressure, temperature, density, viscosity, etc., appropriate to mid latitudes, released by the ICAO.
- Iranian Space Agency, Iran's governmental space agency.
- Israeli Space Agency, Israel's governmental space agency.
- Italian Space Agency, Italy's governmental space agency.
- Independent Schools Association (Australia), a grouping of schools primarily based in Sydney, Australia, for the purposes of sporting competitions.
- Independent Schools Association (UK), one of the oldest of the independent schools’ organisations in the UK. The association is a constituent association of the Independent Schools Council
- Institute for the Study of the Americas, a research institute associated with the University of London's School of Advanced Study
- International School of the Americas, a magnet school located in San Antonio, Texas.
- International School Amsterdam, an international school in the Netherlands.
- International School of Arizona, a not-for-profit school located in Scottsdale, Arizona.
- International School of Aleppo, the only international school in Syria and it's located in Aleppo city
- International Studies Association, an association of political science and international relations scholars
- Investigative Skills Assessment, part of some GCSE Science Syllabii
- Instituto Superior de Arte an art school in Havana, Cuba
- Intensive Support Amount a component of education funding in Ontario 1998-2005, worth $12,000 (level 2) or $27,000 (Level 3) per year, per claimed pupil supposedly to fund one-on-one support; claims doubled to about C$1 billion between 2002 and 2004.
ISA can also refer to:
- Intelligent speed adaptation
- Information System Audit
- Intelligence Support Activity, a special operations unit of the U.S. Army.
- Infectious salmon anemia, a viral disease of salmon.
- Institut de Sélection Animale, a poultry breeding company based in Saint–Brieuc, France.
- International Security Alliance, a fictional spy agency on the NBC soap opera Days of our Lives.
- International Shakespeare Association, an international academic association based in Stratford-upon-Avon, UK.
- International Sign Association, a trade-organization of sign producers.
- International Society of Arboriculture, a non-profit botanical organization.
- International Sociological Association, a non-profit organization in the fields of sociology and the social sciences.
- International Standard Atmosphere, a definition of pressure, temperature, humidity and so forth, under the SI convention.
- Interplanetary Strategic Alliance, an alliance in the video game Killzone and its sequels.
- International Symbol of Access, an image of a stylized person in a wheelchair against a blue background, meant to designate handicap accessibility at a glance.
- Interstellar Alliance, an alliance in Babylon 5 to fight the Shadows.
- Irish Sailing Association, the governing body for sailing in Ireland.
- Independent safety assessment, a type of safety audit.
- Independent Safeguarding Authority, a body created in England, Wales and Northern Ireland to help prevent unsuitable people from working with children and vulnerable adults.
- Grupo ISA, a Colombian utility.