ACI

ACI is an acronym that may refer to:

* Access Control Instruction, an LDAP attribute.
* Accusativus cum infinitivo, a construction in Latin grammar
* Adjacent-channel interference, power from a signal in an adjacent channel
* Air Cargo Inc, an organization that provides information to the freight forwarding industry
* Airports Council International, international trade group of the world's commercial aviation industry, based in Geneva, Switzerland
* American Competitiveness Initiative, a federal program intended to help America maintain competitiveness
* American Constitutional Initiative, a non-profit organization that promotes progressive change
* Alderney Airport, from its IATA airport code
* Agincourt Collegiate Institute a secondary school located in Toronto, Canada
* American Concrete Institute
* Andersen Cascade Impactor, a device to measure the Fine Particle Dose of a Drug
* "Air Crash Investigation", an alternate name for "Mayday" (TV series)
* Albertson College of Idaho, now known as the College of Idaho, a small liberal-arts college in Idaho
* Association Cambiste Internationale-originally Forex Clubs,the Financial Markets Association, founded in 1955
* Automatic Channel Installation, a system that some TVs use to automatically set up the TV channels
* [http://www.aciworldwide.com ACI Worldwide] , an electronic payment solutions company
* Automatic Car Identification, a railroad barcode system that preceded Automatic Equipment Identification
* Automobile Club d'Italia, a member of the FIA
* ACI, the ICAO code for Aircalin
* Aurora Cable Internet, a digital cable television, cable internet and VOIP provider in Aurora, OntarioAci is also the shortened form of the local name of the Sicilian city Acireale.