| Term | Definition |
| ulterior | situated beyond and often questionable |
| ultimate | final; not susceptible to further analysis |
| ultimatum | last demand; warning |
| umbrage | resentment; anger; sense of injury or insult |
| unaccountable | inexplicable; unreasonable or mysterious |
| unanimity | complete agreement |
| unassailable | not subject to question; not open to attack |
| unassuaged | unsatisfied; not soothed |
| unassuming | modest |
| unbridled | violent |
| uncanny | strange; mysterious |
| unconscionable | unscrupulous; excessive |
| uncouth | outlandish; clumsy; boorish |
| unction | the act of anointing with oil |
| unctuous | oily; bland; insincerely suave |
| underlying | fundamental; lying below |
| undermine | weaken; sap |
| underscore | emphasize; underline |
| undulating | moving with a wave like motion |
| unearth | dig up |
| unearthly | not earthly; weird |
| unequivocal | plain; obvious |
| unerringly | infallible |
| unexceptionable | not offering any basis of criticism; entirely acceptable |
| unfaltering | fixed and unchanged in purpose or action; steadfast |
| unfeigned | genuine; real |
| unfettered | liberated; freed from chains |
| unfledged | immature |
| unfrock | to strip a priest or minister of church authority |
| ungainly | awkward; clumsy; unwieldy |
| unguent | ointment |
| uniformity | sameness; monotony |
| unilateral | one-sided |
| unimpeachable | blameless and exemplary |
| uninhibited | unrepressed |
| unintimidating | unfrightening |
| unique | without an equal; single in kind |
| unison | unity of pitch; complete accord |
| universal | characterizing or affecting all; present everywhere |
| unkempt | disheveled; uncared for in appearance |
| unmitigated | unrelieved or immoderate; absolute |
| unobtrusive | not readily noticed or seen; inconspicuous; not blatant |
| unpalatable | distasteful; disagreeable |
| unprecedented | novel; unparalleled |
| unprepossessing | unattractive |
| unravel | disentangle; solve |
| unrequited | not reciprocated |
| unruly | disobedient; lawless |
| unsavory | distasteful; morally offensive |
| unscathed | unharmed |
| unseemly | unbecoming; indecent; poor taste |
| unsightly | ugly |
| unsullied | untarnished |
| untenable | indefensible; not able to be maintained |
| untoward | unfortunate or unlucky; adverse; unexpected |
| untrammeled | without limits or restrictions |
| unwarranted | unjustified; groundless; undeserved |
| unwieldy | awkward; cumbersome; unmanageable |
| unwitting | unintentional; not knowing |
| unwonted | unaccustomed |
| upbraid | severely scold; reprimand |
| uproarious | marked by commotion; extremely funny |
| upshot | outcome |
| urbane | suave; refined; elegant |
| urchin | mischievous child |
| ursine | bearlike; pertaining to a bear |
| usurp | seize another's power or rank |
| usury | The practice of lending money and charging the borrower interest, especially at an exorbitant or illegally high rate |
| utopia | ideal place; state or society |
| uxorious | excessively devoted to one's wife |
| vacillate | waver; fluctuate |
| vacuous | empty; lacking in ideas; stupid |
| vagabond | wanderer; tramp |
| vagary | an erratic, extravagant or unpredictable manifestation, action or notion ; caprice; whim |
| vagrant (adj) | stray; random |
| vagrant (n) | homeless wanderer |
| vainglorious | boastful; excessively conceited |
| valedictory | pertaining to fairwell |
| valid | logically convincing; sound legally acceptable |
| validate | confirm; ratify |
| valor | bravery |
| vampire | ghostly being that sucks the blood of the living |
| vanguard | forerunners; advance forces |
| vantage | position giving an advantage |
| vapid | dull and unimaginative; insipid and flavorless |
| vaporize | turn into vapor (steam, gas, fog, etc.) |
| variegated | many colored |
| vassal | in feudalism, one who hold land of a superior lord |
| vaunted | boasted; bragged; highly publicized |
| veer | change in direction |
| vegetate | live in a monotonous way |
| vehement | forceful; intensely emotional; with marked vigor |