| Abbreviation | Definition |
|---|---|
| UNDV | Undervoltage |
| UNEX | University-Class Explorers |
| UNISAT | United Satellite LTD |
| UNISAT | UNIted SATellite, LTD. |
| UNIV | Universal |
| UNLCH | Unlatch |
| UNLK | Unlock |
| UOF | User Operations Facility |
| UOT | Universal Oxidation Test |
| UP | Unsolicited Proposal |
| UP | Upper |
| UPLK | Uplink |
| UPN | Unique Project Number |
| UPP | User Parameter Processing |
| UPS | Upright Perigee Stage |
| UPTLM | Uplink Telemetry |
| UQS | Unacceptable Quality System |
| UR | Universal Rocket |
| UR | Unsatisfactory Report |
| UR | Upper Right |