| Abbreviation | Definition |
|---|---|
| UNCLE | United Network Command For Law And Enforcement |
| UNCLE | United Network Command Of Law And Enforcement |
| UNITE | Unlawful Narcotics Investigation Treatment and Education |
| UNT | Untied |
| UO | Under Oath |
| UOF | Youth Offenders Facility |
| UOJ | Unified Organization for Justice |
| UPACP | Unique Planted Abbreviation for Copyright Protection |
| UPD | Unknown Purpose Defense |
| UPL | Un-limited Product Liability |
| UPN | United Protectors Network |
| UPPSC | Uttar Pradesh Public Service Commission |
| UR | Universal Royalty |
| URESA | Uniform Reciprocal Enforcement of Support Act |
| URP | Universal Referral Program |
| URPC | Uniform Rules for the Probate Court |
| USAA | United States Arbitration Act of 1925 |
| USAPATRIOTACT | Uniting & Strengthening of America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism |
| USCA | United States Code Annotated |
| USCR | United States Custom Regulations |