| Abbreviation | Definition |
|---|---|
| UIV | United Indians of Virginia |
| UIV | Untaxed Income Verification |
| UJ | The Union Jack |
| UKN | Unknown |
| UL | Underwriter Laboratory, a U.S. government agency that controls and monitors lighting rules and safety |
| ULP | Unfair Labor Practice |
| ULW | Universal Living Wage |
| UMA | Universal Multipurpose Agency |
| UMC | Uniform Mechanical Code |
| UMRA | Unfunded Mandates Reform Act |
| UNDGND | Underground |
| UNDP | United Nations Development Programmes |
| UNEP | United Nations Environment Program |
| UNESCO | United Nations Educational, Scientific, and Cultural Organization |
| UNICOR | Federal Prison Industries, Inc. |
| UNITED | Using New Ideas To Encourage Democracy |
| UNO | United Nations Observer |
| UNO | Un-Named Organization |
| UNV | University |
| UOF | Unusual Order Form |