| Abbreviation | Definition |
|---|---|
| AAA | Authority Authorization AAA |
| AAA | Autonomous Administrative Authority |
| AAEA | Association of African Election Authorities |
| AAI | Airports Authority of India |
| AAIA | Air Accident Investigation Authority |
| AALA | Adventure Activities Licensing Authority |
| AALA | Adventurous Activities Licensing Authority |
| AAOCC | Authority Accuracy Objectivity Currency and Coverage |
| AARA | Access and Amendment Refusal Authority |
| ABCA | Ausable Bayfield Conservation Authority |
| ABCD | Authority Bias Coverage And Date |
| ABEI | Authority of Broadcasting and Electronic Information |
| ABIM | American Board of Internal Medicine |
| ABO | Authorities Budget Office |
| ABRS | Authority of British Riding Schools |
| ACA | Allied Control Authority |
| ACAA | Ada Conformity Assessment Authority |
| ACAA | Allegheny County Airport Authority |
| ACFA | Aged Care Financing Authority |
| ACMA | Australian Communications and Media Authority |