ACI

ACI may refer to:

In education

 * Agincourt Collegiate Institute a secondary school located in Toronto, Canada
 * Albertson College of Idaho, now known as the College of Idaho, a small liberal-arts college in Idaho
 * American Collegiate Institute, Izmir Amerikan Lisesi, located at İzmir, Turkey

In transportation

 * Aero Club of India, the apex body of all flying clubs and the governing body for air sports in India
 * Aircalin, an airline (ICAO code: ACI)
 * 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 Montreal, Canada
 * Alderney Airport, by IATA airport code
 * Alternate Concepts, a transportation management company in the United States
 * Aviators Code Initiative, an organization advancing flight safety and professionalism

Other businesses and organizations

 * ACI Worldwide, a payments software company
 * Adriatic Croatia International Club, a chain of marinas in Croatia
 * ACI (conglomerate), one of the largest Bangladeshi conglomerates
 * Albertsons Companies, Inc., an American supermarket chain
 * American Concrete Institute, a non-profit standards-developing organization
 * American Constitutional Initiative, a non-profit organization that promotes progressive change
 * Anti-Corruption Ireland, political group created by Gemma O'Doherty
 * Arch Coal inc., A major U.S. coal mining company
 * Aurora Cable Internet, a digital cable television, cable internet and VOIP provider in Aurora, Ontario
 * Automobile Club d'Italia, a member of the Fédération Internationale de l'Automobile
 * Aviazione Cobelligerante Italiana, the air force of the Royalist "Badoglio government" in southern Italy during the last years of World War II

Places

 * Acireale, Sicilian city sometimes abbreviated Aci
 * Aci Castello (Sicilian: Jaci Casteddu), a city and comune in the Province of Catania in Sicily, Italy
 * Jaci (river), also called the Aci
 * Acı, Pasinler

Science and technology

 * Adjacent-channel interference, power from a signal in an adjacent channel
 * Application container image, a specification for the format and environment of virtualization containers, initiated by CoreOS
 * Cisco Application Centric Infrastructure, Cisco's implementation of software-defined networking
 * Automatic Car Identification, a railroad barcode system that preceded the automatic equipment identification
 * Autologous chondrocyte implantation, a medical treatment for articular cartilage damage
 * An alternate name for the nitronate moiety

Other uses

 * Assassin's Creed I, the first entry in the long-running Assassin's Creed series.
 * Accusative and infinitive a.k.a. accusativus cum infinitivo, a construction in Latin grammar
 * Ace Combat Infinity
 * Air Crash Investigation, an alternate name for the television series Mayday
 * Aka-Cari language, an extinct Great Andamanese language
 * American Competitiveness Initiative, a federal program intended to help America maintain competitiveness
 * Acis (Italian: Aci) of Acis and Galatea in Greek mythology