- Academy of Military Medical Sciences (AMMS) of the PLA Academy of Military Science
- Academy of Music,Hong Kong Baptist University
- Academy of Sciences of Cuba
- Academy of stage audiovisual and Film Studies，Saint Joseph University
- Academy of Yingtian Prefecture
- Acadia National Park
- Acadians
- académie
- acai
- A. C. Aitken
- A. C. Aitken (1895—1967)
- Acajutla
- acalculia
- A-calculus
- a calendar file
- a call to arms
- a call to arms about vanquishing mara
- Acamar
- AC amplifier
- AC and DC hybrid connection
- acanthamoeba
- acanthocephaliasis
- acanthocephalosis in pig
- acanthocephalosis in poultry
- acanthodians