| Anderson Cascade Impactor | Academic & Science |
| Applied Computational Intelligence | Academic & Science |
| Automation and Control Institute | Academic & Science |
| l'Association Cartographique Internationale | Academic & Science |
| Alderney (one of The Channel Islands) | Airport Code |
| Accounting Compliance International | Business |
| ARCH Coal, Inc. | Business |
| Association of Cambiste Internationale | Business |
| American Concrete Institute | Business |
| Apartment Consultants Inc | Business |
| Automation Components Inc | Business |
| Advantage Career Institute | Business |
| Administrative Concepts Inc | Business |
| Air Cargo, Inc. | Business |
| Aurora Cable Internet | Business |
| A Concrete Idea | Business |
| Advanced Concepts, Inc. | Business |
| Affordable Comfort Inc | Business |
| Associated Communication Inc | Business |
| ASHI Certified InspectorjsdhouhofhACI | Business |
| Accelerated Care Inc | Business |
| Ashi Certified Inspector | Certifications |
| Avid Certified Instructor | Certifications |
| Academy for Community Inclusion | Community |
| Automobil Club Italiano | Community |
| Awana Clubs International | Community |
| American Conference Institute | Community |
| Automatic Channel Installation | Community |
| Association of Commerce and Industry | Community |
| Association des Chercheurs Iraniens | Community |
| Autocad Color Index | Computing |
| Advanced Commercial Information | Computing |
| Add with Carry Immediate | Computing |
| Adjacent Channel Interference | Computing |
| Audio Codec Interface | Computing |
| Autodesk Certified Instructor | Computing |
| Association Chanteheux Informatique | Computing |
| Annotated Cached Information | Computing |
| Artificial Cybernetic Intelligence | Computing |
| Assassins Creed Identity | Computing |
| After Clean Inspection | Electronics |
| Automatic Component Insertion | Electronics |
| Accrued Coupon Income | General |
| Application Communication Interface | General |
| Arizona Correctional Industries | General |
| Access Control Integration | General |
| Access Control Information | General |
| Acceptable Chronic Intake | General |
| Assistant Camera Interface | General |
| Accessory Control Interface | General |
| Auto Chassis International | General |
| Active Curve Illumination | General |
| Audi Club International | General |
| Automotive Component Industries | General |
| Auto Classics International | General |
| Automatic Car Identification | General |
| Atoz Club Indonesia | General |
| All Car Index | General |
| Amicale Citroen Internationale | General |
| Aveo Club Indonesia | General |
| Accord Club Indonesia | General |
| Auto Components India | General |
| Autocar India | General |
| Automatic Cargo Identification | General |
| Agya Club Indonesia | General |
| Autoliv China Inflator | General |
| Allied Construction Industries | General |
| Application Centric Infrastructure | General |
| American Color Imaging | General |
| A—hole Correlation Index | General |
| Active Communications International | General |
| Anal Cranial Inversion | General |
| After Clone Induction | General |
| Accelerated Cost Improvement | General |
| Artificial Cartilage Implant | General |
| Azure Container Instances | General |
| Access Control Instruction | General |
| Army Cyber Institute | Governmental |
| Airport Council International | Governmental |
| Aviazione Cobelligerante Italiana (Italian Co-Belligerent Air Force) | Governmental |
| Automated Car Identification | Governmental |
| American Cleaning Institute | Governmental |
| Advisory Council on Instruction | Governmental |
| Alliance Center for Independence | Governmental |
| American Concrete Institution | Governmental |
| Asociación Cartográfica Internacional | International |
| Alianza Contra la Impunidad | International |
| Automobile Club d'Italia | International |
| Airports Council International | International |
| Accusativus Cum Infinitivum | International |
| Agence Consiliere Immobiliere | International |
| Acute Coronary Insufficiency | Medical |
| Anabolic Catabolic Index | Medical |
| Autologous Chondrocyte Implantation | Medical |
| Agency for Clinical Innovation | Medical |
| Advancing care information | Medical |
| Allocated Configuration Item | Military and Defence |
| Army Counter-intelligence | Military and Defence |
| Assign Call Inhibit | Military and Defence |
| Access Control Interface | Networking |
| Alderney, Channel Islands, United Kingdom | Regional |
| African Culture Institute | Regional |
| Alameda County Industries | Regional |
| Automatic Calibration Interface | Softwares |