| Abbreviation | Definition |
|---|---|
| AR | Air Refueling |
| AR | Air Route |
| AR | Armor |
| AR | Army Regulation |
| AR | Army Regulation; Army Reserve |
| AR | Army Reserve |
| AR | Assault Rifle |
| AR | Atlantic Resolve (exercise name) |
| AR | Automatic Rifle |
| AR/AAV | Armored Reconaissance/Airborne Assault Vehicle |
| AR/AAV | Armored Reconaissance/Airborne Assault Vehicle |
| AR-1 | Army Reserve in the Continental United States |
| AR-15 | ARmalite model 15 |
| AR-15 | armalite-15 |
| AR-2 | Army Reserve Europe |
| AR-3 | Army Reserve Pre-positioned Afloat |
| AR-4 | Army Reserve Pacific |
| AR-5 | Army Reserve Southwest Asia |
| ARA | Accountability Responsibility Authority |
| ARA | Armada Republica Argentina |