ABA
- A.B.A
- AB Aerotransport
- ABA Chemicals
- ABA Games
- ABA League
- ABA League Second Division
- ABA problem
- ABA routing transit number
- Aba (disambiguation)
- Abakan International Airport
- Abas (disambiguation)
- Abba (disambiguation)
- Aberdare railway station
- Abscisic acid
- Abé language
- Académie des Beaux-Arts (Kinshasa)
- Accredited Business Accountant
- Alabama Baptist Association
- Alabama Broadcasters Association
- Altbachisches Archiv
- Amateur Boxing Association of England
- American Bandmasters Association
- American Bandy Association
- American Bankers Association
- American Bantam Association
- American Baptist Association
- American Bar Association
- American Basketball Association
- American Basketball Association (2000–present)
- American Bell Association International
- American Beverage Association
- American Bicycle Association
- American Birding Association
- American Booksellers Association
- American Bridge Association
- American British Academy
- American Bus Association
- Antiquarian Booksellers Association
- Applied behavior analysis
- Architectural Barriers Act of 1968
- Asahi Broadcasting Aomori
- Association of Black Anthropologists
- Australian Banking Association
- Australian Basketball Association
- Australian Blue Asbestos
- Australian Booksellers Association
- Australian Breastfeeding Association
- Australian Broadcasting Authority