| Abbreviation | Definition |
|---|---|
| NZWA | New Zealand Weightlifting Academy |
| NZWA | New Zealand Windsurfing Association |
| O | Olympics |
| O | Out |
| O | Outdoor |
| OAA | Ontario Association Of Archers |
| OAB | Official At Bat |
| OAC | Ohio Athletic Conference |
| OACW | Ohio Athletic Conference Wrestling |
| OACWC | Ohio Athletic Conference Wrestling Championship |
| OAFA | Orkney Amateur Football Association |
| OAFC | Oakland A's Fan Coalition |
| OASIS | Oldham Athletic Supporters In The South |
| OASL | Ohio Amateur Soccer League |
| OAT | Outdoor Adventure Training |
| OATW | Ohio Against The World |
| OB | Offensive Bonus |
| OB | Organized Baseball |
| OB | Out Of Bounds |
| OBA | On Base Average |