| Abbreviation | Definition |
|---|---|
| ULA | Underground Literary Alliance |
| ULTRA | Ultimate List of Talisman Related Articles |
| UM | Unsolved Mysteries |
| UME | The Ultimate Movie Experience |
| UMG | Urban Music Guide |
| UMI | Unified Media Interface |
| UMI | Union Mundial pro Interlingua |
| UMI | University Microfilms, Incorporated |
| UMM | Urban Male Magazine |
| UMOL | Unlocking the Mystery Of Life |
| UMQ | Useless Movie Quotes |
| UMR | Ultimate Metal Reviews |
| UMR | Underground Media Revolution |
| UMS | Universal Media Server |
| UMZ | Unimatrix Zero |
| UNCLE | United Network Command For Law Enforcement |
| UNESCO | United Nations Educational, Scientific, and Cultural Organization |
| UNN | Underground News Network |
| UNP | University of Nagoya Press |
| UOR | Ultimate Oldies Radio |