ACI
- ACI (conglomerate)
- ACI Worldwide
- Accusative and infinitive
- Ace Combat Infinity
- Aci Castello
- Acireale
- Acis and Galatea
- Acı, Pasinler
- Adjacent-channel interference
- Adriatic Croatia International Club
- Aero Club of India
- Agincourt Collegiate Institute
- Air Cargo Inc.
- Aircalin
- Airports Council International
- Aka-Cari language
- Albertsons
- Alderney Airport
- Alternate Concepts
- American Collegiate Institute
- American Competitiveness Initiative
- American Concrete Institute
- American Constitutional Initiative
- Anti-Coercion Instrument
- Anti-Corruption Ireland
- Application container image
- Arch Coal
- Assassin's Creed
- Assassin's Creed (video game)
- Aurora Cable Internet
- Autologous chondrocyte implantation
- Automobile Club d'Italia
- Aviators Code Initiative
- Aviazione Cobelligerante Italiana
- Cisco
- College of Idaho
- European Union
- Jaci (river)
- KarTrak
- Mayday (Canadian TV series)