| Acronym | Definition |
|---|
| UD | Update |
| UD | University of Dayton (Dayton, OH) |
| UD | University of Delaware |
| UD | Unanimous Decision |
| UD | Usted (Spanish: Formal You) |
| UD | Urban Dictionary (slang web site) |
| UD | Upper Deck |
| UD | Udine (Friuli Venezia Giulia, Italy) |
| UD | Universal Design |
| UD | University of Dallas (Irving, TX, USA) |
| UD | Utility Dog |
| UD | Undisclosed |
| UD | Undead (gaming) |
| UD | User Defined |
| UD | Usaha Dagang (Indonesian trading company) |
| UD | Utenriksdepartementet (Department of Foreign Affairs) |
| UD | Upper Division |
| UD | Up/Down |
| UD | Under Development |
| UD | Unidirectional |
| UD | Unified Defense |
| UD | Uniform Design (mathematics) |
| UD | University of Dubuque (Iowa) |
| UD | Ugly Duckling (band) |
| UD | Universal Declaration of Human Rights (UN; also seen as UDHR) |
| UD | University of Denver |
| UD | User Domain |
| UD | Under Duress |
| UD | Urban District |
| UD | University of Detroit |
| UD | Unlawful Detainer |
| UD | Unión Democrática (Spanish: Democratic Union) |
| UD | Underdark (roleplaying games, Dungeons & Dragons) |
| UD | United Defense |
| UD | Ultimate Doom (game) |
| UD | Universitair Docent |
| UD | United Devices, Inc. |
| UD | Underwater Demolition |
| UD | Ultimate Disney (website) |
| UD | Underwater Diving |
| UD | Unit Diary |
| UD | Undesirable Discharge |
| UD | United Diesel |
| UD | Universal Default |
| UD | Utility Degree (AKC Obedience Degree) |
| UD | Ut Dictum (Latin: As Directed) |
| UD | Under Defeat (game) |
| UD | Utility Driver |
| UD | Unidoom (gaming clan) |
| UD | Uniquely-Decodable |
| UD | Uniquely Decipherable |
| UD | Utilisation Declaration |
| UD | Unitary District (UK) |
| UD | Ulcerative Dermatosis |
| UD | Unit Designator |
| UD | Urban Disease |
| UD | Unofficially Dropped (grading system) |
| UD | Unable to Approve Departure for the Time Specified |
| UD | Unabsorbed Depreciation (accounting/finance) |
| UD | Unremove Directory (Norton Utilities) |
| UD | Under Digging (pipeline construction) |
| UD | UltraDiagnostics (South Attleboro, MA) |