| Abbreviation | Definition |
|---|---|
| AR | Autistic Referee |
| ARABS | American Registry Of Arab Bred Sporthorses |
| ARAC | Advanced Recreational Avalanche Course |
| ARAC | All Races All Classes |
| ARB | Australian Racing Board |
| ARBH | Association Royale Belge de Hockey |
| ARC | Active Race Control |
| ARC | Adventure Racing Canada |
| ARC | Alloy Racing Composites |
| ARC | American Roundball Corporation |
| ARC | Arcane Roleplayers Consortium |
| ARC | Association of Rover Clubs |
| ARC | Atlantic Rally For Cruisers |
| ARCA | Automobile Race Car Association |
| ARCA | Automobile Racing Club of America |
| ARF | Amazing Race Fan |
| ARG | Aspenridge Ratscha Gamers |
| ARGO | A Romanian Gymnastics Organization |
| ARGO | Allegheny Regional Gaming Organization |
| ARI | Arizona Diamondbacks |