| 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 |
