| Abbreviation | Definition |
|---|---|
| AAAH | Australian Association for Adolescent Health |
| AAMSU | All Assam Manipuri Student Union |
| AAMSU | All Assam Manipuri Students Union |
| AAMSU | All Assam Minorities Students Union |
| AAMSU | All Assam Moran Students Union |
| AANH | Aviation Association of New Hampshire |
| AArC | Architectural Artisans Collaborative |
| AASU | African American Students Union |
| AASU | All Assam Students Union |
| AASU | Asian American Student Union |
| AAU | Allgemeine Arbeiter Union |
| AAU | Amateur Athlete Union |
| AAU | Amateur Athletics Union |
| AAU | Amature Athletic Union |
| AAU | American Athletic Union |
| AAWG | Algonquin Area Writer's Group |
| AAWU | African American Workers Union |
| AAWU | All Afghan Women Union |
| ABEU | Air Botswana Employees' Union |
| ABMSU | All Bodo Minority Students Union |