ACU
- ACU (Utrecht)
- Abilene Christian University
- Achutupo Airport
- Acu Publishing
- Ahram Canadian University
- Ajayi Crowther University
- Altura Credit Union
- American City University
- American Coalition for Ukraine
- American Conservative Union
- Arab Customs Union
- Arizona Christian University
- Army Combat Uniform
- Asian Clearing Union
- Asian Currency Unit
- Assassin's Creed Unity
- Assiniboine Credit Union
- Association of Commonwealth Universities
- Australian Catholic University
- Auto-Cycle Union
- Açu
- Açu River
- List of FIA member organisations
- Novell Open Enterprise Server
- Pariquera-Açu
- Superporto do Açu
- Supreme Commander (game)
- US Navy