| Abbreviation | Definition |
|---|---|
| AATA | Arkansas Athletic Trainers Association |
| AAU | Amateur Athletic Union |
| AAU | Amateur Athletics Union |
| AAUC | Amateur Athletic Union of Canada |
| AAYA | Anishinabe Athletic Youth Association |
| ABAC | Avila Bay Athletic Club |
| ABS | Abdomen Six pack |
| ABW | Athletics for a Better World |
| AC | Athletic Club |
| ACA | Academics Community and Athletics |
| ACAA | Allegheny Christian Athletic Association |
| ACAA | Amateur Competitive Athletics Association |
| ACAA | American Collegiate Athletic Association |
| ACAA | Atlantic Colleges Athletic Association |
| ACAA | Atlantic Collegiate Athletic Assoc |
| ACAC | Alberta Colleges Athletics Conference |
| ACAC | Allen County Athletic Conference |
| ACAC | Atlantic Coast Athletic Club |
| ACAF | Addison Community Athletics Foundation |
| ACB | Athletic Club of Bend |