- useful
- usual
- unable
- unlikely
- urban
- upper
- unique
- unknown
- unusual
- unemployed
- universal
- ultimate
- urgent
- unexpected
- uncertain
- unfair
- unhappy
- unnecessary
- upset
- unfortunate
- uncomfortable
- ugly
- useless
- unpleasant
- unacceptable
- unaware
- unconscious
- underground
- uniform
- unchanged
- unreasonable
- unwilling
- unsuccessful
- unclear
- uneasy
- unlawful
- unprecedented
- understandable
- unwanted
- unfamiliar
- unsatisfactory
- ulcerative
- unionist
- unlimited
- unstable
- unsuitable
- unpredictable
- uneven
- uncommon
- unlike
- unpopular
- undesirable
- unofficial
- unsure
- up-to-date
- unpaid
- unmarried
- unrealistic
- unrelated
- upward
- unbeaten
- unbelievable
- unaffected
- unlucky
- undue
- unpublished
- unseen
- unused
- unreliable
- utter
- untouched
- unskilled
- unnatural
- unanimous
- unwelcome
- upright
- unitary
- unequal
- unmistakable
- unwise
- unimportant
- unavoidable
- unsafe
- unnoticed
- unfinished
- unjust
- utmost
- untidy
- unavailable
- unfit
- ubiquitous
- unconditional
- unthinkable
- unilateral
- unbearable
- unresolved
- unauthorised
- unfavourable
- unattractive
- underwater
- unambiguous
- usable
- unspoken
- unspecified
- unmarked
- uncompromising
- unqualified
- unreal
- uncontrolled
- unbroken
- untrue
- undoubted
- unhealthy
- undisturbed
- unidentified
- unkind
- unexplained
- unequivocal
- utilitarian
- unhelpful
- untreated
- urinary
- undercover
- unleaded
- unanswered
- unscrupulous
- unorthodox
- undisclosed
- uppermost
- unnamed
- unproductive
- uncanny
- unwell
- unforeseen
- unchallenged
- unprepared
- uncontrollable
- ultraviolet
- unborn
- unfounded
- utopian
- undeniable
- undecided
- unoccupied
- unjustified
- unarmed
- unregistered
- unheard
- unrivalled
- unrestricted
- unspoilt
- unruly
- uninterrupted
- unforgettable
- unscathed
- unfriendly
- uphill
- unprotected
- unconstitutional
- uncomplicated
- unmoved
- undisputed
- unchanging
- unconventional
- unsecured
- unconvincing
- unconcerned
- unsuspecting
- unwarranted
- unaltered
- unsteady
- unprofitable
- unsold
- upper-class
- unworthy
- unaccustomed
- unattended
- unsympathetic
- unwritten
- unchecked
- unsightly
- unparalleled
- unimpressed
- unworkable
- uneconomic
- unclean
- unintended
- untoward
- untold
- untenable
- untrained
- unobtrusive
- upstream
- ungrateful
- uninterested
- unopposed
- unconvinced
- unsolicited
- unplanned
- uncritical
- uninteresting
- unremarkable
- unharmed
- unimaginable
- unintelligible
- unwary
- unaided
- unsolved
- undemocratic
- unenforceable
- unreported
- unstoppable
- undetected
- unfettered
- unstructured
- unpalatable
- undeveloped
- upmarket
- unaccompanied
- undemanding
- unfashionable
- unwieldy
- uncaring
- user-friendly
- unicameral
- uncharacteristic
- unassailable
- unbiased
- unreadable
- unmet
- unfaithful
- unperturbed
- uneventful
- undivided
- unwashed
- umbilical
- uneducated
- unexplored
- unhurt
- unsophisticated
- undifferentiated
- unlisted
- unauthorized
- unsavoury
- unsupported
- unfulfilled
- unimaginative
- unyielding
- underdeveloped
- undamaged
- unrepresentative
- unkempt
- uninhabited
- unbeatable
- unspeakable
- undefined
- undaunted
- unsound
- unremitting
- unrepentant
- unopened
- unresponsive
- undignified
- unattainable
- unintentional
- unrecognised
- undiscovered
- uninhibited
- unanticipated
- unholy
- unsung
- untypical
- uninformed
- unlit
- unrelenting
- unassuming
- unpromising
- unstressed
- unsuited
- untimely
- unquestioned
- unsuspected
- upbeat
- unthinking
- ultrasonic
- unethical
- uptight
- unsatisfied
- unannounced
- uncontroversial
- unjustifiable
- unmanageable
- unhurried
- undeterred
- unusable
- unforgivable
- unobserved
- unguarded
- unregulated
- unrestrained
- unpretentious
- urbane
- unsmiling
- unenviable
- untroubled
- uncommitted
- unending
- unscientific
- unwitting
- unrecorded
- unabated
- unitarian
- uninvited
- untried
- unlicensed
- unsigned
- uninitiated
- unfocused
- unruffled
- undefeated
- upcoming
- untapped
- unbounded
- unacknowledged
- unforgiving
- unfailing
- unsubstantiated
- unselfish
- unconfirmed
- undistinguished
- ungainly
- untested
- unhindered
- untitled
- unanswerable
- unsustainable
- unbridled
- undisciplined
- unattached
- ungrammatical
- unmatched
- uninspiring
- underprivileged
- unaccountable
- unproblematic
- uncharted
- uncut
- unashamed
- up-and-coming
- unrecognized
- unconstrained
- ulterior
- unshaven
- unstated
- unflattering
- undated
- unloved
- uncluttered
- unlabelled
- uncompetitive
- ursodeoxycholic
- unprovoked
- undisguised
- untouchable
- unearthly
- unobtainable
- uncouth
- unknowing
- unmodified
- uncooperative
- undiminished
- unsupervised
- unheeded
- unpaired
- unspoiled
- undiluted
- unsaturated
- unprofessional
- unfeeling
- unshakeable
- unmoving
- unscheduled
- unquestioning
- unabashed
- unfilled
- uncomprehending
- unseemly
- untrustworthy
- unmitigated
- unrewarding
- unprincipled
- unrequited
- unwavering
- undying
- untrammelled
- unenthusiastic
- unbreakable
- unassisted
- underhand
- unsurpassed
- undeclared
- uncoordinated
- untainted
- unblemished
- unrecognisable
- unrepresented
- undeserved
- unemotional
- unadorned
- unimpeded
- unincorporated
- unadulterated
- unimpressive
- unelected
- unfathomable
- unquestionable
- unrelieved
- unrecognizable
- unknowable
- unheated
- uneconomical
- unequalled
- uncooked
- untamed
- unclassified
- unswerving
- unworldly
- urethral
- unread
- uninjured
- unencumbered
- unpolluted
- unceasing
- unexciting
- uninspired
- unreleased
- underweight
- unimpaired
- up-to-the-minute
- unmentionable
- unaccounted
- unexceptional
- understaffed
- unidirectional
- unseeing
- uncorrelated
- undetectable
- unimpeachable
- unsystematic
- unclaimed
- unexploded
- unidentifiable
- unsocial
- uterine
- unpunished
- unrefined
- unalterable
- unascertained
- unspectacular
- undetermined
- uneaten
- unremarked
- unrealized
- unmixed
- untutored
- unquoted
- unmediated
- unforgiven
- unsalted
- unerring
- uninsured
- uncontaminated
- undefended
- unbridgeable
- unselfconscious
- undersized
- unhygienic
- unearned
- uncompleted
- unconverted
- unprepossessing
- upstanding
- unbelieving
- unapproachable
- uncollected
- ultrastructural
- uninhabitable
- ungodly
- unlined
- unreconstructed
- uncrossed
- ungenerous
- unemployable
- unquantifiable
- unfurnished
- uncontested
- uncharitable
- unglamorous
- unbleached
- unambitious
- uninformative
- unflinching
- unconscionable
- unconsidered
- unheard-of
- unchallengeable
- unforeseeable
- uncultivated
- unplayable
- undersea
- uncongenial
- unexamined
- unbecoming
- ungracious
- unendurable
- unromantic
- unlovely
- undocumented
- unmistakeable
- ungovernable
- unspecific
- uncrowded
- unappreciated
- unsaleable
- unvarying
- unasked
- unorganised
- unpainted
- unschooled
- untranslated
- unsociable
- unconditioned
- unilinear
- unobstructed
- unseeded
- unpatriotic
- uppity
- unturned
- unadjusted
- unmolested
- unchangeable
- unaffiliated
- unworried
- unproven
- undigested
- unprocessed
- unclimbed
- unctuous
- unclothed
- unco-operative
- unreasoning
- unrepeatable
- unexceptionable
- unsurprised
- unintelligent
- uncontentious
- unexpressed
- unobservable
- unproved
- unformed
- unorganized
- unsentimental
- unsullied
- unconsolidated
- uncommunicative
- unshaded
- unexpired
- unpasteurised
- unselected
- uninvolved
- unrewarded
- unflappable
- unfree
- unwholesome
- untiring
- unpronounceable
- unreformed
- unheralded
- undiagnosed
- uninfected
- undreamed
- upgradable
- undesired
- untaxed
- untraceable
- unshed
- uraemic
- unmemorable
- unapproved
- unclouded
- unleavened
- untreatable
- unstained
- unalloyed
- uncorrected
- undramatic
- uncivilised
- untarnished
- unipolar
- up-front
- unissued
- unshielded
- underarm
- unvarnished
- unpaved
- unblocked
- unpolished
- unquenchable
- unimagined
- unreserved
- unforced
- unenlightened
- underpowered
- uninviting
- unsubtle
- undirected
- unacquainted
- undistorted
- uncharged
- unavailing
- unimproved
- unreachable
- underemployed
- unconfined
- unachievable
- upfront
- unadventurous
- unobjectionable
- uncalled
- unpremeditated
- unplaced
- undimmed
- unhampered
- uninfluenced
- unoriginal
- undemonstrative
- unblinking
- uniplex
- upgradeable
- universalistic
- unwaged
- unladylike
- unsweetened
- unfiltered
- unarguable
- unhistorical
- ungentlemanly
- unvented
- uncarpeted
- unglazed
- undernoted
- unripe
- uncreative
- unaudited
- unfenced
- untended
- unlovable
- unbowed
- uttermost
- unseasonal
- unconcealed
- unprejudiced
- useable
- upstate
- unpleasing
- uncorroborated
- unviable
- unprintable
- unassociated
- unsinkable
- uncivilized
- unilateralist
- uncommercial
- unfunded
- unnumbered
- unfeminine
- unsliced
- unpardonable
- unutterable
- unmentioned
- undeformed
- ultradian
- unmanly
- uric
- unmissable
- uncensored
- unpolitical
- unburied
- unmotivated
- unfertilized
- unpropitious
- uncomplimentary
- uncompressed
- underage
- unelectable
- uncurtained
- uncounted
- uncircumcised
- unamused
- undersigned
- unfruitful
- undescribed
- undismayed
- unsupportive
- ultramarine
- uproarious
- unbolted
- unreflective
- unmeasured
- unregenerate
- unexploited
- unparliamentary
- ultrabasic
- unmusical
- unventilated
- unmanaged
- unamended
- unsought
- unperceived
- unconjugated
- unanalysed
- unliquidated
- unserviceable
- undeserving
- unsupportable
- unspecialized
- unnoticeable
- unfunny
- unpopulated
- unspent
- unquiet
- unshakable
- unprompted
- unhesitating
- undecorated
- untestable
- unworked
- unedited
- unidimensional
- unwed
- undermanned
- undischarged
- unfrequented
- unmapped
- uncoloured
- undiscriminating
- uninitialised
- unreconciled
- unquantified
- uptown
- unfussy
- unlooked-for
- unicellular
- unscripted
- uncrowned
- unwonted
- unaffordable
- ureteric
- unseasonable
- unprovable
- unmerchantable
- unprovided
- unconvicted
- undefinable
- unbranded
- unpublicised
- unarticulated
- unsanitary
- unflagging
- unsighted
- unreceptive
- unpeopled
- uncombed
- unvisited
- unstimulated
- unvoiced
- unceremonious
- unresolvable
- unappealing
- unfertilised
- unheroic
- uncalled-for
- unwarrantable
- unappreciative
- unspotted
- unrevealing
- unthreatened
- uncustomary
- unbaptised
- unpeeled
- uncorrupted
- unhealed
- undercooked
- unresearched
- uncleared
- unapologetic
- unchaperoned
- unrespectable
- undersubscribed
- unexposed
- unchartered
- unabsorbed
- undefiled
- unreactive
- unpruned
- urological
- unready
- unallocated
- uncared
- unframed
- unescorted
- unfaltering
- unbarred
- undelivered
- underfinanced
- unfancied
- unneeded
- undreamed-of
- untalented
- uncited
- unaddressed
- unclassifiable
- unfeasible
- unredeemed
- unadopted
- uncreated
- up-beat
- unregarded
- untransfected
- unedifying
- unabridged
- unwounded
- unstaffed
- unoperated
- unlettered
- unremembered
- undrained
- unremunerative
- unchurched
- undreamt
- ungloved
- underwired
- uncountable
- unrepeated
- unsorted
- unrighteous
- untruthful
- unexcavated
- unconquerable
- unconquered
- unflustered
- unexecuted
- unfazed
- unwinnable
- undyed
- unattributed
- untraced
- unrounded
- univocal
- unexplainable
- undistributed
- uneatable
- unpractised
- uninterpretable
- unrehearsed
- unpredicted
- unshockable
- unmerited
- uncoated
- unwrinkled
- undiplomatic
- unwelcoming
- ultrasonographic
- unrepaired
- unsatisfying
- unachieved
- unassigned
- unenclosed
- unproblematical
- unperfumed
- ungoverned
- unburned
- unwinking
- unmated
- unhedged
- unlamented
- unsurprising
- uninsurable
- unmeasurable
- unscreened
- uncontainable
- uncomplexed
- unpractical
- unbothered
- ultra-high
- untranslatable
- usurious
- uncanonical
- unguided
- unvalidated
- uncultured
- unformulated
- unbranched
- unreached
- unrevealed
- unindexed
- unrealizable
- unpressed
- unary
- unchristian
- unfalsifiable
- unsensational
- unlighted
- unaspirated
- unemphatic
- uniformitarian
- unlikeable
- unreclaimed
- unassertive
- unamplified
- undiscussable
- uncivil
- unknotted
- undersize
- unexcited
- unstinted
- untasted
- unstirred
- unfocussed
- unskilful
- unfed
- unsurfaced
- unbusinesslike
- unsurpassable
- unrooted
- unfeigned
- uncompensated
- unlooked
- unmounted
- ungrounded
- uncontrived
- unsporting
- unexpurgated
- unforgiveable
- unpinned
- unequipped
- unaccented
- unrealisable
- unalike
- unweathered
- unfractionated
- unsanctioned
- unembarrassed
- unreasoned
- unconfident
- untrimmed
- unverifiable
- unestablished
- undamped
- unmannerly
- undercapitalised
- uncosted
- upper-case
- undreamt-of
- uxorious
- unprivileged
- unassimilable
- uncaused
- unanalysable
- unserved
- unripened
- uncemented
- unstinting
- undesignated
- unpadded
- unroadworthy
- unmatchable
- unexercised
- unteachable
- unprogressive
- uncertificated
- upriver
- underhanded
- unresectable
- uninsulated
- unroped
- unattributable
- unintegrated
- unconsummated
- unresisting
- uncached
- untenanted
- undistracted
- undeviating
- unappetising
- ungallant
- under-ripe
- under-the-counter
- uninterpreted
- untransformed
Note: these words have been obtained from Wiktionary and have been classified and improved through automated computer linguistics processes.