| Area Concentration Achievement Test | Academic & Science |
| สมาคมวิศวกรรมปรับอากาศแห่งประเทศไทย | Academic & Science |
| Air-Conditioning Engineering Association of Thailand | Academic & Science |
| Association of Church Accountants and Treasurers | Accounts and Finance |
| Accreditation Council for Accountancy and Taxation | Accounts and Finance |
| Automated Customer Account Transfer | Accounts and Finance |
| Arctic Cat, Inc. | Business |
| Advisory Committee on Automation in Transportation | Business |
| Advisory Committee on Accessible Transportation | Business |
| Airport Community Advisory Team | Business |
| Acyl Coa: Cholesterol Acyltransferase | Chemistry |
| Asian Coalition Against Tobacco | Community |
| Area Concentration Achievement Tests | Community |
| Aqua City Actors Theatre | Community |
| Automatic Collision Avoidance Technology | Computing |
| Applied Cognition And Technology | Computing |
| Alphacat | Cryptocurrency |
| Atlanta Cask Ale Tasting | General |
| Automated Customer Account Transfers | General |
| American Center for the Alexander Technique | General |
| Assistive Context Aware Toolkit | General |
| Advanced Compartmental And Transit | General |
| Acyl Cholesterol Acyl Transferase | General |
| Automated Client Account Transfer | General |
| Automatic Customer Account Transfer | General |
| Additional Cooperative Acceptance Testing | General |
| Advanced Crash Avoidance Technologies | General |
| Amateurs et Collectionneurs d'Automobiles de Touraine | General |
| Aged Care Assessment Team | Governmental |
| Alberta Council on Admissions and Transfer | Governmental |
| Albuquerque Cat Action Team | Medical |
| Acquisition Category | Military and Defence |
| Aeromedical Evacuation Command Augmentation Team | Military and Defence |
| Alaska Community Action on Toxics | Regional |
| Alaska Cat Adoption Team | Regional |
| Alaska Center for Appropriate Technology | Regional |
| Aironet Configuration Administration Tool | Softwares |
