| ulcer | úlcera |
| ulcerate | ulcerarse |
| ulcerous | ulceroso |
| Ulcinj | Ulcinj |
| Uldin | Uldin |
| Ulead Systems | Ulead Systems |
| ULEB | Unión de Ligas Europeas de Baloncesto |
| ULEB Cup | Copa de la ULEB |
| ulexite | ulexita |
| Ulf von Euler | Ulf von Euler |
| Ulfilas | Ulfilas |
| Ulic Qel-Droma | Ulic Qel-Droma |
| Ulises de la Cruz | Ulises de la Cruz |
| Ulisse Aldrovandi | Ulisse Aldrovandi |
| Ulla | Unified Link Layer API |
| Ullapool | Ullapool |
| Ullevi | Estadio Ullevi |
| Ullr | Ull |
| Ulluco | Ullucus tuberosus |
| Ulm | Ulm |
| Ulm Cathedral | Catedral de Ulm |
| Ulmaceae | Ulmaceae |
| Ulmen | Ulmus minor |
| ulna | cúbito |
| Ulpian | Ulpiano |
| Ulrica | Ulrica |
| Ulrich Jasper Seetzen | Ulrich Jasper Seetzen |
| Ulrich of Augsburg | Ulrico de Augsburgo |
| Ulrichen | Ulrichen |
| Ulrika Eleonora of Sweden | Ulrica Leonor de Suecia |
| Ulrike Meinhof | Ulrike Meinhof |
| Ulriksdal Palace | Palacio de Ulriksdal |
| Ulster | Ulster |
| Ulster Cycle | Ciclo de Ulster |
| Ulster Defence Association | Asociación en Defensa del Ulster |
| Ulster Unionist Party | Partido Unionista del Ulster |
| Ulster Volunteer Force | Fuerza Voluntaria del Ulster |
| Ulster Volunteers | Fuerza Voluntaria del Ulster |
| ulterior | ulterior |
| ulterior motive | segunda intención |
| ultimate | final |
| Ultimate fate of the Universe | Destino último del universo |
| Ultimate Iron Man | Ultimate Hombre de Hierro |
| Ultimate Spider-Man | Ultimate Spider-Man |
| ultimately | finalmente |
| ultimatum | ultimátum |
| Ultimatum game | Juego del ultimátum |
| Ultra High Definition Video | Televisión de ultra alta definición |
| ultra light rail | tren ultraligero |
| Ultra low frequency | Ultra baja frecuencia |
| Ultra Seven | Ultraseven |
| Ultra short wave | VHF |
| Ultra-high-temperature processing | UHT |
| Ultra-light | Aviación ultraligera |
| Ultra-Mobile PC | PC Ultra Móvil |
| Ultra-short wave | VHF |
| Ultra-wideband | Ultrawideband |
| ultraconservative | intransigente |
| Ultradian | Ritmo ultradiano |
| ultraism | ultraísmo |
| Ultraist | ULTRA |
| Ultraliberalism | Ultraliberalismo |
| Ultralight aviation | Aviación ultraligera |
| ultranationalism | ultranacionalismo |
| ultraright | ultraderecha |
| Ultras | Ultras |
| Ultrasauros | Ultrasauros |
| Ultrasaurus | Ultrasaurus |
| ultrasonic | ultrasónico |
| Ultrasonic sound | Ultrasonido |
| ultrasonography | ultrasonografía |
| ultrasound | ultrasonido |
| ultrasound scan | ecografía |
| ultrastructure | ultraestructura |
| ultraviolet | ultravioleta |
| Ultraviolet astronomy | Astronomía ultravioleta |
| Ultraviolet background | Fondo ultravioleta |
| Ultraviolet camera | Cámara para el ultravioleta |
| Ultraviolet catastrophe | Catástrofe ultravioleta |
| Ultraviolet colors | Índice de color en el UV |
| Ultraviolet continuum | Continuo ultravioleta |
| Ultraviolet detector | Detector de ultravioletas |
| Ultraviolet filter | Filtro ultravioleta |
| Ultraviolet index | Índice UV |
| Ultraviolet line | Línea en el ultravioleta |
| Ultraviolet luminosity | Luminosidad en el ultraviolet |
| Ultraviolet object | Objeto untravioleta |
| ultraviolet radiation | radiación ultravioleta |
| Ultraviolet spectrographs | Espectrógrafo ultravioleta |
| Ultraviolet telescope | Telescopio de rayos ultraviol |
| Ultraviolet-visible spectroscopy | Espectroscopía ultravioleta-visible |
| Ultzama | Ulzama |
| Ulugh Beg | Ulugh Beg |
| ululate | ulular |
| Uluru | Uluru |
| Uluç Ali Reis | Uluj Alí |
| Ulva | Ulva |
| Ulva lactuca | Ulva lactuca |
| Ulyanovsk | Uliánovsk |
| Ulyanovsk Oblast | Óblast de Ulyanovsk |
| Ulysses | Odiseo |
| Ulysses S. Grant | Ulysses S. Grant |
| Ulúa River | Río Ulúa |
| Uma | UMA |
| Uma Thurman | Uma Thurman |
| Umar | Umar ibn al-Jattab |
| Umar ibn Hafsun | Omar ibn Hafsún |
| Umayyad | Dinastía de los Omeyas |
| Umayyad conquest of Hispania | Invasión musulmana de la Península Ibérica en el siglo VIII |
| Umayyad conquest of North Africa | Conquista musulmana del Magreb |
| UMB | Memoria alta |
| Umbanda | Umbanda |
| Umbardacil | Telumehtar-Umbardacil |
| umbel | umbela |
| Umberto Boccioni | Umberto Boccioni |
| Umberto Eco | Umberto Eco |
| Umberto Giordano | Umberto Giordano |
| Umberto I of Italy | Humberto I |
| Umberto II of Italy | Humberto II |
| Umberto Nobile | Umberto Nobile |
| umbilical | umbilical |
| umbilical bandage | faja |
| umbilical cord | cordón umbilical |
| umbilical hernia | hernia |
| umbilicate | umbilicado |
| umbilicus | ombligo |
| umbrageous | sombreado |
| umbrella | centralizador |
| Umbrella Cockatoo | Cacatua alba |
| Umbrella Corporation | Corporación Umbrella |
| umbrella stand | paragüero |
| umbrella term | hiperónimo |
| Umbrellabird | Cephalopterus ornatus |
| Umbrello UML Modeller | Umbrello |
| Umbria | Umbría |
| Umbrian | umbra |
| Umbriel | Umbriel |
| Umbundu language | Idioma umbundu |
| UMD | Universal Media Disc |
| Umeboshi | Umeboshi |
| Umeå | Umeå |
| Umeå Municipality | Umeå |
| Umeå University | Universidad de Umeå |
| Umhlanga | Umhlanga |
| umlaut | diéresis |
| Umm al-Fahm | Umm al-Fahm |
| Umm al-Quwain | Umm al Qaywayn |
| Umm Khultum | Umm Kalzum |
| Umm Kulthum | Umm Kalzum |
| Umm Qais | Umm Qais |
| ummah | umma |
| Ummo | Ummo |
| umpire | árbitro |
| umpteen | multitud |
| umpteenth | enésima |
| Umrah | Umrah |
| Umyak | Umiak |
| UN | ONU |
| Un Argentino en New York | Un argentino en New York |
| Un ballo in maschera | Un baile de máscaras |
| UN Charter | Carta de las Naciones Unidas |
| Un chien andalou | Un perro andaluz |
| UN Convention on the Rights of the Child | Convención sobre los Derechos del Niño |
| Un giorno di regno | Un giorno di regno |
| Un Paso Adelante | Un paso adelante |
| UN Peacemaker | UN Peacemaker |
| UN reports Rwandan refugees repatriated by force | Los refugiados ruandeses en Burundi son repatriados a la fuerza según informe de la ONU |
| UN Secretary General | Secretaría General de Naciones Unidas |
| UN Secretary-General | Secretaría General de Naciones Unidas |
| UN Security Council | Consejo de Seguridad de Naciones Unidas |
| un- | in- |
| unabashed | descarado |
| unabashedly | desinhibidamente |
| unabated | no disminuido |
| unabating | incesante |
| unable | impotente |
| unable to work | incapacitado |
