Jesus, called Isa in Arabic.

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.

Independent safety assessment, a type of safety audit.

The Islamic view of Jesus, in particular.

Investigative Skills Assessment, part of some GCSE Science Syllibii

Instrumentation, Systems, and Automation Society, formerly the Instrument Society of America, a professional organization for instrument engineers.

Intelligent speed adaptation

Intelligence Support Activity, a special-forces operations unit of the U.S. Army.

Interplanetary Strategic Alliance, an alliance in the video game Killzone and its sequels.

Individual Savings Account, a financial account for investment in the UK with special tax rules.

Mount Isa, Queensland, a city in northwest Queensland, Australia.

Industry Standard(s) Architecture, a now-obsolete I/O bus standard for IBM-compatible PC motherboards.

International Seabed Authority, an intergovernmental body based in Kingston, Jamaica established to organize and control all mineral-related activities in international seabed areas.

Iranian Space Agency, Iran's governmental space agency.

Microsoft Internet Security and Acceleration Server, a Microsoft server product.

Isa, Nigeria, a local government area in Sokoto State

Infectious salmon anemia, a viral disease of salmon.

Israeli Space Agency, Israel's governmental space agency.

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.

ISA is a three-letter acronym that may stand for: In politics:

International School of the Americas, a magnet school located in San Antonio, Texas.

Isa (dance), a local variation of a Jota.

Independent Schools Association, a group of schools in New South Wales, Australia.

Italian Space Agency, Italy's governmental space agency.

International Standards on Auditing, professional standards for the performance of audits of financial information.

Israel Securities Authority, the Israeli regulator of financial and stock market.

International Sign Association, a trade-organization of sign producers.

International School of Arizona, a not-for-profit school located in Scottsdale, Arizona.

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.

Institute for the Study of the Americas, a research institute associated with the University of London's School of Advanced Study

International Sociological Association, a non-profit organization in the fields of sociology and the social sciences.

Isa (album), a 2004 album by Enslaved.

Irish Sailing Association, the governing body for sailing in Ireland.

Isa (computer science), a relationship between objects; for instance, an apple tree "is a" tree.

Interstellar Alliance, an alliance in Babylon 5 to fight the Shadows.

International School Amsterdam, an international school in the Netherlands.

ISA platform ("NOS"), an operating system software for Nokia mobile telephones.

Internal Security Act, laws that enable the executive government of a jurisdiction to preserve the internal security of the nation.

International Society of Arboriculture, a non-profit botanical organization.

Isa (moth), a moth genus.

Isa (name), a common Arabic name. Also a shortened form of the Montenegrin name Isailo.

International Searching Authority, a patent office performing prior art searches during the prosecution of international (patent) applications under the Patent Cooperation Treaty.

International Security Alliance, a fictional spy agency on the NBC soap opera Days of our Lives.