| Abbreviation | Definition |
|---|---|
| UMP | Umpire |
| UNBA | United Natural Bodybuilding Association |
| UNF | Ukrainian National Federation |
| UNIT | United Notorious Intoxication Team |
| UNRC | Upper Natoma Rowing Club |
| UNW | Ulitmate Nonstop Wrestling |
| UOA | United Officials Association |
| UOD | Units Of Destruction |
| UOE | Ultima Online Extreme |
| UoR | Union of Reach |
| UP | Utilizing Potential |
| UPA | Ultimate Players Association |
| UPA | United Poolplayers Association |
| UPA | United Professional Pool Players Association |
| UPAC | University Place Aquatic Club |
| UPF | United Pegasus Foundation |
| UPK | United Parkers Kenpo |
| UPK | United Parker's Kenpo Club |
| UPK | Universal Pasha Karate School |
| UPL | Unified Pool League |