AAT
- A80 (disambiguation)
- Aat (queen)
- Achanalt railway station
- Administrative Appeals Tribunal
- Alpha 1-antitrypsin
- Altay Xuedu Airport
- Alturas Municipal Airport
- An American Translation
- Ancient astronauts
- And Another Thing (disambiguation)
- Anglo-Australian Telescope
- Animal-assisted therapy
- Apple Advanced Typography
- Aquatic Ape Theory
- Armored Assault Tank
- Arvanitika
- Asia Airfreight Terminal
- Aspartate transaminase
- Association of Accounting Technicians
- Ath
- Australian Antarctic Territory
- AutoAlliance Thailand
- Hong Kong Academic Aptitude Test