AAO
- Acer Aspire One
- Administrative Appeals Office
- Aktionsanalytische Organisation
- America's Army
- American Academy of Ophthalmology
- American Academy of Optometry
- American Academy of Osteopathy
- American Association of Orthodontists
- Anaco Airport
- Andrushivka Astronomical Observatory
- Anodic Aluminum Oxide
- Antarctic oscillation
- Ascending aorta
- Australian Astronomical Observatory
- Colonel James Jabara Airport
- D-amino acid oxidase
- L-amino-acid oxidase
- Loc. cit.
- Saharan Arabic