ACU

ACU is a three-letter acronym that may refer to:

* Abilene Christian University, a private Christian university located in Abilene, Texas.
* Achutupo Airport, an airport in Achutupo, Panama with the IATA airport code "ACU".
* American Conservative Union, a large political lobbying group in the United States.
* Army Combat Uniform, the combat uniform worn by the United States Army.
* Asian Clearing Union, an organization that settles international payments between member countries.
* Asian Currency Unit, a proposed unit of Association of Southeast Asian Nations currency
* Assault Craft Unit, military units of the United States Navy that specialize in amphibious warfare.
* Association of Commonwealth Universities, an association that represents over 480 universities from Commonwealth countries.
* Australian Catholic University, Australia's only public Catholic university.
* Auto-Cycle Union, an officially recognised motorcycle governing body of Great Britain.
* Automatic Client Upgrade, a process that will upgrade a computer workstation's Novell client.
* Armoured Command Unit, the key unit in the RTS game Supreme Commander.
* Automovil Club del Uruguay, a member of the FIA

Acu can refer to:
* Açu River in Brazil