| Abbreviation | Definition |
|---|---|
| OPSH | OPeration SpaceHog |
| OPSL | Oregon Premier Soccer League |
| OPSL | Orlando Pro Summer League |
| OPST | Ocean Pines Swim Team |
| OPSV | Ostschweizer Poker Sport Verein |
| OPW | Ontario Place West Channel |
| OPWSA | Ontario Provincial Women's Softball Association |
| OQB | Old QuarterBack |
| OQM | Oxfordshire Quality Musclebuilding |
| OQR | Oxfordshire Quality Recreation |
| OR | Olympic Record |
| ORA | Ontario Racing Association |
| ORC | Offshore Racing Council |
| ORC | Ogura Race Clutch |
| ORC | Oyl Riding Club |
| ORCA | Ontario Recreational Canoeing Association |
| ORD | Open Road Driver |
| ORDA | Olympic Regional Development Authority |
| ORDP | Open Road Driver Program |
| ORL | Orion Racing League |