AAS is a three-letter abbreviation with multiple meanings, as described below:

Science and mathematics

• Angle-Angle-Side, a method for showing congruency between triangles.
• ASCII Adjust after Subtraction, an Intel 80x86 processor instruction; see Intel BCD opcodes
• Atomic absorption spectroscopy, a methodology of analytical chemistry

Academia

• Asian American Studies, an academic discipline which studies the experience of people of Asian ancestry in America
• Associate in Applied Science(s), a degree/title conferred on students by a college, university, or professional school on completion of a program of study of two years; see associate's degree

Airports

• Apalapsili Airport (IATA airport code: AAS) in Apalapsili, Indonesia
• Taylor County Airport (IATA airport code: AAS) in Campbellsville, Kentucky, United States

Special-interest groups

• American Antiquarian Society, a learned society and national research library of pre-twentieth century American History and culture
• American Astronautical Society
• American Astronomical Society, a United States society of professional astronomers
• Architectural Association School of Architecture, the oldest independent school of architecture in the United Kingdom
• Arnold Air Society, a professional, honorary, service organization for Air Force officer candidates, associated with Air Force Association
• Association for Asian Studies
• Australian Academy of Science, an independent, government-endorsed society with the general aim of promoting science
• Assyrian Academic Society
• American Anti-Slavery Society

Other uses

• Ateliers Aéronautiques de Suresnes, a defunct French aircraft manufacturing company

AAS