| Abbreviation | Definition |
|---|---|
| UPC | United Pentecostal Church |
| UPCI | United Pentecostal Church International |
| UPCS | United Presbyterian Church of Scotland |
| UPS | Unity Peace Serenity |
| UPV | Ulster Protestant Volunteers |
| UPY | United Presbyterian Youth |
| UR | Uber Reincarnation |
| UR | Universal Reconciliation |
| URCS | Upper Room Christian School |
| URF | University Radio Falmer |
| URF | Upper Room Fellowship |
| URJ | Union for Reform Judaism |
| UROK | Universal Reception Of Karma |
| URPC | Upper Room Pentecostal Church |
| US | United Souls |
| USCC | United States Christian Commission |
| USCCA | United States Catholic Catechism for Adults |
| USCCB | United States Conference of Catholic Bishops |
| USCMA | U S Catholic Mission Association |
| USF | U Stay Forever |