AA

AA, Aa, Double A, or Double-A may refer to:

Arts, entertainment and media

Alcoholics Anonymous, an international fellowship dedicated to helping alcoholics peer to peer in sobriety
A. A. Arms, a defunct firearms manufacturer
Aerolíneas Argentinas, an Argentine airline (logo used to consist of two A's)
Air Asia, an Asian multinational low cost carrier
Alcoa, an American aluminum-producing company (stock symbol AA)
American Airlines, major American full-service airline (IATA airline code, logo used to consist of two A’s)
Anadolu Agency, a state-run press agency in Turkey
Audio-Animatronics, used at the Disney Parks
Academia de Artes, Mexico
Amalgamated Association of Iron and Steel Workers, a former union in the United States
Andecha Astur, an Asturian nationalist party
Architectural Association School of Architecture, London, United Kingdom
Astrological Association of Great Britain, London, United Kingdom
Auswärtiges Amt, the Foreign Office of Germany
Danish Association of Architects (Akademisk Arkitektforening)
The AA (formerly The Automobile Association), a British motoring organization
AA Ireland, an Irish automotive services company
AA Motoring Trust, a former British road safety charity operated by The AA that was merged to form the IAM Motoring Trust

A∴A∴, a spiritual organization created in 1907 by Aleister Crowley
Abhisamayalankara, or Abhisamaya-alaṅkāra, a Mahayana Buddhist text
Augustinians of the Assumption, a congregation of Catholic religious (priests and brothers)
Statue of A'a from Rurutu, a wooden fertility-god sculpture from the Pacific island of Rurutu
"A is A", an expression of the law of identity: each thing is identical with itself

aa, Latin-script digraph used in the orthographies of Dutch, Finnish and other languages
aa, representation of letter Å in several Scandinavian languages
aa, a romanization of Arabic letter alif ا
Ꜳ, an orthographic ligature
Afar language (ISO 639-1 language code aa)
Aa (Bengali), a Bengali letter

Aa (surname), a Scandinavian surname, including a list of people with this name
Van der Aa (surname), a Dutch surname, including a list of people with this name
Aa (architect), an architect in ancient Egypt
Anthony Armstrong (writer) (1897–1972), Anglo-Canadian writer who used the pseudonym A.A.

Aabach (Aare), a tributary of the Aare in canton of Aargau
Aabach (Greifensee), or Ustermer Aa, a river in canton of Zürich
Aabach (Obersee), a tributary of Obersee (Zürichsee), in canton of St. Gallen
Aabach (Seetal), a river in the cantons of Lucerne and Aargau, runs through Lake Hallwyl
Chli Aa (Sempachersee), a tributary of Lake Sempach in the canton of Lucerne
Engelberger Aa, a river in the cantons of Obwalden and Nidwalden, tributary of Lake Lucerne
Gross Aa (Sempachersee), a tributary of Lake Sempach in the canton of Lucerne
Mönchaltorfer Aa, a tributary of Greifensee in canton of Zürich
Sarner Aa (river), a river in Obwalden, tributary of Lake Lucerne

AA amyloidosis, a form of amyloidosis related to serum amyloid A
Amino acid, often abbreviated aa when indicating positions in a peptide sequence (e.g., aa 120–150)
Antiandrogen, a drug which blocks the effects of androgens
Aplastic anemia, a rare disease
Arachidonic acid, a polyunsaturated fatty acid
Advanced Architecture, original name of Amiga Advanced Graphics Architecture
Anti-aliasing, various techniques for mitigating certain signal processing artifacts
Atlas Autocode, a computer programming language
AA, a proprietary digital audio format of Audible.com
Authoritative Answer, in DNS, a flag for a query answer
AA postulate of Euclidean geometry
Anti-aircraft, in military use
Abampere (aA), the CGS unit of current
Attoampere (aA), a unit of electric current equal to 10⁻¹⁸ Ampere
AA tree, named after Arne Andersson
AA, the abbreviation for azidoazide azide
AppArmor

Double-A (baseball) or Class AA, a classification level in Minor League Baseball since 1912
American Association (1882–1891), a professional baseball league in the United States from 1882 to 1891
American Association (1902–1997), a professional baseball league in the United States from 1902 to 1962 and 1969 to 1997
American Association of Professional Baseball, a professional baseball league in the United States and Canada since 2006
Athletics Australia, national sporting organisation in Australia

AA Highway, a state highway in Northern Kentucky
Ann Arbor Railroad (1895–1976), a defunct railroad in Ohio and Michigan
Ann Arbor Railroad (1988), a railroad operating in Ohio and Michigan
K line, a defunct line on the New York City Subway, formerly called "AA"
NZR A^A class, a locomotive class operated by the New Zealand Railways Department