| Under A Violet Moon | Under a Violet Moon |
| Under The Bridge | Under the Bridge |
| Under the Iron Sea | Under the Iron Sea |
| underdog | underdog |
| Underground | Underground culture |
| Undergroundstrip | Underground comix |
| Underneath your clothes | Underneath Your Clothes |
| understatement | understatement |
| Une Seule Nuit | Une Seule Nuit |
| UNED | Universidad Nacional de Educación a Distancia |
| UNEF I | United Nations Emergency Force |
| Unesco | UNESCO |
| Unfabulous | Unfabulous |
| unfair | unfair |
| Ungangan | Aleut |
| Ungerhausen | Ungerhausen |
| Ungheni | Ungheni |
| Ungoliant | Ungoliant |
| Ungoofaaru | Ungoofaaru |
| Unhappily Ever After | Unhappily Ever After |
| Unia Janikowo | Unia Janikowo |
| Unicaat | Unique copy |
| UNICEF | UNICEF |
| Uniciteit | Uniqueness quantification |
| Unico Wilhelm van Wassenaer | Unico Wilhelm van Wassenaer |
| Unicode | Unicode |
| Unidentified Flying Object | Unidentified flying object |
| unidirectioneel | unidirectional |
| unie | union |
| Unie der Socialistische Sovjetrepublieken | USSR |
| Unie van Atrecht | Union of Arras |
| Unie van Baptistengemeenten in Nederland | Union of Baptist Churches in the Netherlands |
| Unie van Christen- en Centrum-Democraten | Union of Christian and Centre Democrats |
| Unie van Democratische Krachten | Union of the Democratic Forces |
| Unie van Indochina | Indo-China |
| Unie van Islamitische Rechtbanken | Islamic Courts Union |
| Unie van Lublin | Union of Lublin |
| Unie van Rechtse Krachten | Union of Right Forces |
| Unie van Utrecht | Union of Utrecht |
| Unie van Vrije Democraten | Union of Free Democrats |
| Unie van Zuid-Afrika | Union of South Africa |
| Unie voor een Europa van Nationale Staten | Union for Europe of the Nations |
| Uniegebouwen | Union Buildings |
| Uniejów | Uniejów |
| uniek | only |
| Uniek factorisatiedomein | Unique factorization domain |
| Unieterritorium | Union Territory |
| Uniface | Uniface |
| unificatie | unification |
| Unified Modeling Language | Unified Modeling Language |
| uniform | equable |
| Uniform B | Uniform and insignia of the Boy Scouts of America |
| Uniform NL | Uniform and insignia of the Boy Scouts of America |
| Uniform Resource Locator | Uniform Resource Locator |
| Uniformitarianisme | Uniformitarianism |
| uniformiteit | uniformity |
| uniformjas | tunic |
| Unije | Unije |
| unilateraal | unilateral |
| Unilever | Unilever |
| Unio | Unio |
| Union | Union |
| Union Centroamericana de Fútbol | Union Centroamericana de Fútbol |
| Union de la Gauche Socialiste | Union de la gauche socialiste |
| Union Démocratique et Socialiste de la Résistance | Democratic and Socialist Union of the Resistance |
| Union Flag | Union Jack |
| Union Internationale des Chemins de fer | International Union of Railways |
| Union Jack | Union Jack |
| Union Luxemburg | Union Luxembourg |
| Union of European Football Associations | UEFA |
| Union pour la Démocratie Française | Union for French Democracy |
| Union pour un Mouvement Populaire | Union for a Popular Movement |
| Union Solingen | Union Solingen |
| Union Sportive Monastir | Union Sportive Monastir |
| Union Valdôtaine | Valdotanian Union |
| Unione dei Democratici Cristiani e Democratici di Centro | Union of Christian and Centre Democrats |
| Unipotent | Unipotency |
| Unirally | Uniracers |
| Unirea Urziceni | FC Unirea Voluntari Urziceni |
| uniseks | unisex |
| unisex | unisex |
| unisono | unison |
| Unisys | Unisys |
| unit | unit |
| Unit construction | Unit construction |
| UNITA | UNITA |
| Unitaire Democratische Coalitie | Unitarian Democratic Coalition |
