UD
- Democratic Unification Party
- Democratic Union (Guatemala)
- Hex'Air
- Oud
- Regional decentralization entity of Udine
- Spanish personal pronoun
- UD Trucks
- Ud (cuneiform)
- Udonis Haslem
- Unanimous decision
- United Devices
- United Distillers
- Universal Dependencies
- University of Dallas
- University of Dammam
- University of Dayton
- University of Delaware
- University of Detroit Jesuit High School and Academy
- University of Detroit Mercy
- University of Dublin
- University of Dubuque
- University of Durham
- Unlawful detainer
- Unlock Democracy
- Unterrified Democrat
- Upper Deck
- Urban Dictionary
- Utenriksdepartementet
- Utrikesdepartementet