| Unincorporated area | Uninflected word | Uninterruptible power supply |
| Union Bridge, Maryland | Union catalog | Union Center, Wisconsin |
| Union Charter Township, Michigan | Union City, Georgia | Union City, Indiana |
| Union City, Michigan | Union City, Tennessee | Union County, Indiana |
| Union County, Kentucky | Union County, New Jersey | Union County, Pennsylvania |
| Union County, South Carolina | Union des Sociétés Françaises de Sports Athlétiques | Union Films |
| Union Gap, Washington | Union Grove, Wisconsin | Union Hill, Illinois |
| Union List of Artist Names | Union of Christendom | Union of Islamic Organisations of France |
| Union of Soviet | Union of Soviet Socialist Republics | Union Parish, Louisiana |
| Union Point, Georgia | Union pour la démocratie française | Union pour un mouvement populaire |
| Union Springs, New York | Union Square, San Francisco | Union Township, Branch County, Michigan |
| Union Township, Grand Traverse County, Michigan | Union, Burnett County, Wisconsin | Union, Door County, Wisconsin |
| Union, Eau Claire County, Wisconsin | Union, Illinois | Union, Iowa |
| Union, Kentucky | Union, Mississippi | Union, Missouri |
| Union, Monroe County, West Virginia | Union, Nebraska | Union, Ohio |
| Union, Oregon | Union, Pierce County, Wisconsin | Union, Rock County, Wisconsin |
| Union, South Carolina | Union, Vernon County, Wisconsin | Union, Waupaca County, Wisconsin |
| UnionFS | Uniontown, Kansas | Uniontown, Kentucky |
| Uniontown, Washington | Unionville Center, Ohio | Unionville, Iowa |
| Unionville, Michigan | Uniopolis, Ohio | UniProt |
| Uniprot web | Unique Ingredient Identifier | Uniramia |
| UNIS | Unit (ring theory) | Unit 731 |
| Unit circle | Unit disk | Unit doses |
| Unit fraction | Unit of analysis | Unit of observation |
| Unit operation | Unit testing | Unitarianism |
| Unitary authority | Unitary state | Unité d'Habitation |
| United 93 (film) | United Aircraft Corporation | United Airlines |
| United Airlines Flight 173 | United Airlines Flight 175 | United Airlines Flight 232 |
| United Airlines Flight 608 | United Airlines Flight 610 | United Airlines Flight 624 |
| United Airlines Flight 93 | United Arab Airlines Flight 869 (1962) | United Arab Airlines Flight 869 (1963) |
| United Arab Emirates | United Arab Emirates Air Force | United Arab Emirates dirham |
| United Arab Emirates football competitions | United Arab Emirates parliamentary election, 2006 | United Armenia |
| United Artists | United Buddy Bears | United Kingdom |
| United Kingdom of Great Britain and Ireland | United Kingdom of Great Britain and Northern Ireland | United Linux |
| United Nations | United Nations Charter | United Nations Climate Change conference |
| United Nations Commission on Human Rights | United Nations Conference on the Standardization of Geographical Names | United Nations Conference on Trade and Development |
| United Nations Convention against Corruption | United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances | United Nations Convention against Torture |
| United Nations Convention on Contracts for the International Sale of Goods | United Nations Convention to Combat Desertification | United Nations Development Program |
| United Nations Development Programme | United Nations Economic and Social Council | United Nations Economic Commission for Europe |
| United Nations Educational, Scientific and Cultural Organization | United Nations Environment Programme | United Nations Fact Finding Mission on the 2014 Israel–Gaza conflict |
| United Nations Fact Finding Mission on the Gaza Conflict | United Nations Framework Convention on Climate Change | United Nations General Assembly |
| United Nations General Assembly Resolution 3379 | United Nations General Assembly Resolution 46/86 | United Nations High Commissioner for Refugees |
| United Nations Human Rights Council | United Nations Industrial Development Organization | United Nations Integrated Mission in East Timor |
| United Nations Interim Administration Mission in Kosovo | United Nations Interim Force in Lebanon | United Nations laissez-passer |
| United Nations Office of the High Representative for the Least Developed Countries, Landlocked Developing Countries and Small Island Developing States | United Nations Office on Drugs and Crime | United Nations Parliamentary Assembly |
| United Nations Partition Plan for Palestine | United Nations Population Fund | United Nations Security Council |
| United Nations Security Council Resolution 1701 | United Nations Security Council Resolution 2042 | United Nations Security Council Resolution 2043 |
| United Nations Security Council Resolution 233 | United Nations Security Council Resolution 234 | United Nations Security Council Resolution 235 |
| United Nations Security Council Resolution 236 | United Nations Security Council Resolution 237 | United Nations Security Council Resolution 240 |
| United Nations Security Council Resolution 242 | United Nations Security Council Resolution 338 | United Nations Security Council Resolution 339 |
| United Nations Security Council Resolution 340 | United Nations Security Council Resolution 341 | United Nations Security Council Resolution 346 |
| United Nations Security Council Resolution 362 | United Nations Security Council Resolution 363 | United Nations Security Council Resolution 368 |
| United Nations Security Council Resolution 369 | United Nations Security Council Resolution 660 | United Nations Security Council Resolution 661 |
| United Nations Security Council Resolution 662 | United Nations Security Council Resolution 678 | United Nations Security Council Resolution 681 |
| United Nations Security Council Resolution 687 | United Nations Security Council Resolution 694 | United Nations Security Council Resolution 726 |
| United Nations Security Council Resolution 799 | United Nations Supervision Mission in Syria | United Nations Support Mission in Libya |
| United Nations Transitional Administration in East Timor | United Parcel Service | United Press International |
| United Principalities | United Provinces of Central Italy | United Russia |
| United States | United States Adopted Name | United States Africa Command |
| United States Air Force | United States Air Force Academy | United States Air Force Thunderbirds |
| United States Army | United States Atomic Energy Commission | United States Attorney |
| United States bombing of the Chinese embassy in Belgrade | United States box office records | United States Census Bureau |
| United States Census, 2000 | United States Census, 2010 | United States Coast Guard |
| United States Conference of Catholic Bishops | United States Congress | United States Constitution |
| United States copyright law | United States Cultural Exchange Programs | United States customary units |
| United States Department of Agriculture | United States Department of Defense | United States Department of Energy |
| United States Department of Health and Human Services | United States Department of State | United States Department of Veterans Affairs |
| United States diplomatic cables leak | United States dollar | United States Environmental Protection Agency |
| United States fiscal cliff | United States Fish and Wildlife Service | United States Geological Survey |
| United States Holocaust Memorial Museum | United States House of Representatives | United States Medical Licensing Examination |
| United States Military Academy | United States National Academy of Sciences | United States National Library of Medicine |
| United States national missile defense | United States Navy | United States occupation of the Dominican Republic (1965–66) |
| United States of Africa | United States of America | United States Olympic Committee |
| United States passport | United States Pharmacopeia | United States Poet Laureate |
| United States presidential election, 2016 | United States Secretary of Commerce | United States Secretary of the Treasury |
| United States Senate | United States Senate Committee on Environment and Public Works | United States Senate Committee on Foreign Relations |
| United States Senate Committee on Veterans' Affairs | United States Supreme Court | United States Virgin Islands |
| United States women's national soccer team | United States-Iran relations | United we stand, divided we fall |
| United World College Maastricht | United World College of the Adriatic | United World Colleges |
| Unitrans | Units of information | Units of measurement |
| Units of textile measurement | Unity (game engine) | Unity (logiciel) |
| Unity (user interface) | Unity Cooperative Company | Unity Linux |
| Unity Village, Missouri | Unity, Clark County, Wisconsin | Unity, Oregon |
| Unity, Trempealeau County, Wisconsin | Unity, Wisconsin | Universal (metaphysics) |
| Universal algebra | Universal approximation theorem | Universal Declaration of Human Rights |
| Universal design | Universal Disk Image Format | Universal gateway |
| Universal grammar | Universal Media Disc | Universal monarchy |
| Universal Music Group | Universal Pictures | Universal Plug and Play |
| Universal property | Universal Serial Bus | Universal set |
| Universal Soldier (1992 film) | Universal Soldier: Day of Reckoning | Universal space |
| Universal Studios | Universal Time | Universalism |
| Universality (philosophy) | Universality–diversity paradigm | Universe |
| Universita Cattolica del Sacro Cuore | Universitas 21 | Universitat zu Wien |
| Université Hassiba Ben Bouali chlef | Université islamique de Say | Universities & Colleges Admissions Service |
| University | University City, Missouri | University College Dublin A.F.C. |
| University College of Opera | University Heights, Iowa | University of al-Jazirah |
| University of al-Qarawiyyin | University of Belgrade | University of Berne |
| University of Birmingham | University of Bologna | University of Bolton |
| University of British Columbia | University of Cairo | University of California |
| University of California Press | University of California, Berkeley | University of California, Irvine |
