| Acronym | Definition |
|---|
| ACI | American Concrete Institute |
| ACI | Airports Council International (formerly Airport Associations Coordinating Council) |
| ACI | Automobile Club d'Italia |
| ACI | Arch Coal Inc |
| ACI | American Competitiveness Initiative (US government) |
| ACI | Access Control Information |
| ACI | Alltel Communications Inc. |
| ACI | Alianza Cooperativa Internacional (Spanish) |
| ACI | Autologous Chondrocyte Implantation |
| ACI | Azione Cattolica Italiana |
| ACI | Audit Committee Institute |
| ACI | Adjacent Channel Interference |
| ACI | Activated Carbon Injection |
| ACI | Alliance Coopérative Internationale |
| ACI | Adult Correctional Institutions (Nebraska) |
| ACI | Access Control Instruction (Netscape) |
| ACI | American Competitiveness Institute (Philadelphia, PA, USA) |
| aCI | Advanced Communications Incorporated (Canton, MI) |
| ACI | Approved Course of Instruction |
| ACI | Applied Computational Intelligence |
| ACI | Andean Counterdrug Initiative |
| ACI | Adriatic Croatia International (Club and Nautical Tourism Company) |
| ACI | Audio Concepts, Inc. |
| ACI | Advanced Commercial Information (Canada) |
| ACI | Accusativus Cum Infinitivo |
| ACI | American Consumer Institute |
| ACI | Albertson College of Idaho |
| ACI | Applied Communications Inc. |
| ACI | Automatic Channel Installation |
| ACI | Association for Conservation Information |
| ACI | AutoCAD Color Index |
| ACI | American Culinary Institute |
| ACI | Adult Correctional Institute (Rhode Island) |
| ACI | Aurora Cable Internet |
| ACI | America's Career Infonet |
| ACI | Automation Creations, Inc (Blacksburg, Virginia) |
| ACI | Ashmore and Cartier Islands |
| ACI | Alloy Casting Institute |
| ACI | Allocated Configuration Identification |
| ACI | Augmentative Communication Inc. |
| ACI | Asset Condition Index |
| ACI | American Conservative Union (Alexandria, VA) |
| ACI | Analytical Condition Inspection |
| ACI | American Combustion Industries Inc. |
| ACI | Autonomy Content Infrastructure |
| ACI | Alderney, Channel Islands, United Kingdom - The Blaye (Airport Code) |
| ACI | Actual Cost Incurred |
| ACI | Administratively Controlled Information |
| ACI | Agincourt Collegiate Institute (Agincourt, Ontario, Canada high school) |
| ACI | Arts and Creative Industries (UK) |
| ACI | Acute Coronary Insufficiency |
| ACI | Apple Computer, Incorporated |
| ACI | Alianza Contra la Impunidad (Spanish: Alliance Against Impunity, Guatemala) |
| ACI | Additional Circuit Information |
| ACI | Ann Clark Associates |
| ACI | Air Combat Intelligence (US DoD) |
| ACI | Agrifood Consulting International |
| ACI | Allied Continental Intermodal (UK) |
| ACI | Assign Call Inhibit |
| ACI | Automatic Component Insertion |
| ACI | Associative Computing, Inc. (now Associative Cognition, Inc.) |
| ACI | Aero Club of India (New Delhi, India) |
| ACI | Advanced Computing Initiative |
| ACI | Advantage Consulting Inc (Annandale, VA) |
| ACI | Advertising Council, Inc. |
| ACI | Agribusiness Council of Indiana |
| ACI | Active Community Initiative (UK) |
| ACI | Air Caledonie, New Caledonia (ICAO code) |
| ACI | African Cultural Initiatives |
| ACI | Automatic Card Identification |
| ACI | Accelerated Capability Initiative |
| ACI | Avataq Cultural Institute |
| ACI | Automated Criminal Investigation |
| ACI | Airborne Controlled Intercept |
| ACI | Acceptable Chronic Intake |
| ACI | Access Channel Integration (HP) |
| ACI | American College Institute (Izmir, Turkey high school) |
| ACI | Alexander Consulting, Inc. |
| ACI | Airborne Control Intercept |
| ACI | Apollo Computers, Incorporated |
| ACI | Access Control Integration, Inc. (Memphis, TN) |
| ACI | Automatic Closure and Interlock |
| ACI | Amplifier Control Intercommunications |
| ACI | Advanced Control Interface |
| ACI | Asset Condition Inspection |
| ACI | Air Controlled Intercept (CIS) |
| ACI | AT Command Interpreter |
| ACI | Anello Consulting Inc (Cocoa, FL) |
| ACI | Amplifier Control Inter-Communication |
| ACI | Arensmeyer Communications, Inc. |
| ACI | Anixter Communication and Integration |
| ACI | Allocated Configuration Item |
| ACI | Access Communications Information |
| ACI | Architectural Communications, Inc. |
| ACI | After Care Instructions (medical) |
| ACI | Automated Coding of Invoices |
| ACI | Appraiser's Choice, Inc |
| ACI | Associate Contractor Integration/Interface |
| ACI | Advanced Consulting Incorporated (Monterey, CA) |
| ACI | Agents Conseil Immobilier |
| ACI | Amherst Consulting Inc (South Portland, ME) |
| ACI | Accurate Contractors Inc |
| ACI | Advanced Consulting and Inspection, LLC (Lakeville, MN) |