OAS

OAS or Oas may refer to:

Chemistry

 * O-Acetylserine, amino-acid involved in cysteine synthesis

Computers

 * Open-Architecture-System, the main user interface of Wersi musical keyboards
 * OpenAPI Specification (originally Swagger Specification), specification for machine-readable interface files for RESTful Web services
 * Oracle Application Server, software platform

Medicine

 * Open aortic surgery, surgical technique
 * Oral allergy syndrome, food-related allergic reaction in the mouth
 * 2'-5'-oligoadenylate synthase, an enzyme
 * OAS1, OAS2, OAS3, anti-viral enzymes in humans

Organizations

 * Office of Aviation Services, agency of the United States Department of the Interior
 * Ontario Archaeological Society, organization promoting archaeology within the Province of Ontario, Canada
 * Organisation Armée Secrète, French dissident terrorist organisation, active during the Algerian War (1954–62), fighting against Algerian independence
 * Organization of American States, continental organization of the Western Hemisphere
 * Oxford Art Society, society for artists in the city of Oxford, England

Transport

 * Oasis LRT station, Singapore, LRT station abbreviation OAS

Other

 * Ohio Auction School, school for auctioneers in Ohio, U.S.
 * Old Age Security, social security payment available to most Canadians aged 65 or older
 * Option-adjusted spread, the yield-curve spread of a fixed-income security, adjusted for the cost of embedded options
 * Oas, Albay, municipality in the Philippines