| U |
Unionist; University |
| UAE |
United Arab Emirates |
| UBC |
University of British Columbia |
| UC |
University College |
| UCAS |
Universities and Colleges Admissions Service |
| UCE |
University of Central England |
| UCH |
University College Hospital (London) |
| UCL |
University College London (University) |
| UCLA |
University of California at Los Angeles |
| UCNW |
University College of North Wales |
| UCS |
University College School |
| UCW |
University College of Wales; Union of Communication Workers |
| UDC |
Urban District Council; Urban Development Corporation |
| UDR |
Ulster Defence Regiment; Union Democrates pour la Veme Republique |
| UE |
United Empire Loyalist (Canada) |
| UEA |
University of East Anglia |
| UFC |
Universities' Funding Council |
| UGC |
University Grants Committee (later UFC) |
| UK |
United Kingdom of Great Britain and Ireland 1801-1922; United Kingdom of Great Britain and Northern Ireland 1922-; used chiefly of peerage and baronetage creations of |
| UKAEA |
United Kingdom Atomic Energy Authority |
| UKLF |
United Kingdom Land Forces |
| UMDS |
United Medical and Dental Schools |
| UMIST |
University of Manchester Institute of Science and Technology |
| UN |
United Nations |
| UNA |
United Nations Association |
| unc |
uncle |
| UNIFEM |
United Nations Development Fund for Women |
| Univ |
University - College (Oxford) |
| unm |
unmarried |
| UNO |
United Nations Organization |
| UNRRA |
United Nations Relief and Rehabilitation Administration |
| UP |
United Provinces - India; Utter Pradesh; United Presbyterian |
| URC |
United Reformed Church |
| US(A) |
United States (of America) |
| USAAF |
United States Army Air Force |
| USAF |
United States Air Force |
| USAR |
United States Army Reserve |
| USC |
University of Southern California |
| USDAW |
Union of Shop Distributive and Allied Workers |
| USMC |
United States Marine Corps |
| USN |
United States Navy |
| USNR |
United States Naval Reserve |
| USPG |
United Society for the Propagation of the Gospel |
| USS |
United States Ship |
| USSR |
Union of Soviet Socialist Republics |
| UT |
Utah |
| Utd |
United |
| UU |
Ulster Unionist |
| UWE |
University of the West of England |
| UWIST |
University of Wales Institute of Science and Technology |
