| Term | Definition |
| ulterior | unstated |
| ultimate | final |
| unaccountable | inexplicable |
| unanimity | complete agreement |
| unassailable | not subject to question |
| unassuming | modest |
| unbridled | violent |
| uncanny | strange |
| unconscionable | excessive |
| uncouth | clumsy |
| unctuous | oily |
| underlying | weaken |
| underscore | emphasize |
| undulating | moving with a wavelike motion |
| unearth | dig up |
| unequivocal | plain |
| unerringly | infallibly |
| unfathomable | incomprehensible |
| unfetter | liberate |
| unfrock | to strip priest or minister of authority |
| ungainly | awkward |
| uniformity | sameness |
| unimpeachable | blameless |
| uninhibited | unrepressed |
| unintimidating | unfrightening |
| unique | without an equal |
| universal | affecting all |
| unkempt | uncared for in appearance |
| unmitigated | unrelieved |
| unobtrusive | not blatant |
| unpalatable | distasteful |
| unprecedented | novel |
| unprepossessing | unattractive |
| unravel | solve |
| unrequited | not reciprocated |
| unruly | lawless |
| unseemly | in poor taste |
| unsightly | ugly |
| unstinting | not holding back |
| untenable | indefensible |
| unwieldy | awkward |
| unwitting | unintentional |
| upbraid | severely scolded |
| uproarious | extremely funny |
| upshot | outcome |
| urbane | suave, elegant |
| usurp | seize another's power or rank |
| utopia | ideal place |
| vacillate | waver |
| vacuous | empty |
| vegabond | wanderer |
| vagrant | homeless |
| valedictory | pertaining to farewell |
| valid | legally acceptable |
| validate | confirm |
| vampire | ghostly being that sucks on blood |
| vanguard | advance guard of a military force |
| vantage | position giving an advantage |
| vapid | dull |
| vaporize | turn to vapor |
| variegated | many colored |
| veer | change |
| vehement | forceful |