UDF
- All You Need Is Kill
- UDF 2457
- UDF 423
- Ulster Defence Force
- Ultra Deep Field
- Union Defence Force (South Africa)
- Union Defence Force (UAE)
- Union of Democratic Forces (disambiguation)
- Union pour la Démocratie Française
- Uniqueness Database File
- United Dairy Farmers
- United Democratic Forces
- United Democratic Forces of Belarus
- United Democratic Forum Party
- United Democratic Front (Botswana)
- United Democratic Front (Kerala)
- United Democratic Front (Malawi)
- United Democratic Front (Mizoram)
- United Democratic Front (Namibia)
- United Democratic Front (Pakistan)
- United Democratic Front (South Africa)
- United Democratic Front (South Sudan)
- Universal Disk Format
- User-defined function