upright.adjective
being in a vertical.position or direction (upright posts between the electical wires); erect in posture or carriage; adhering.strictly to moral.principles (she was a woman upright in character, as were these women); righteous; having integrity
upright.adverb
vertically (walk upright)
upright.noun,.plural.uprights
a perpendicular position; verticality; something, such as a goal post, that stands upright
uprightly.adverb
uprightness.noun,.plural.uprightnesses

undesirable.adjective
not likely to please; objectionable (undesirable intrusions); not wanted (undesirable weather)
undesirable.noun
something.regarded as undesirable (the snake in the yard was an unwanted visitor)
undesirably.adverb
undesirability.noun,.plural.undesirabilities
undesired.adjective
not desired; unwanted; unsought, unwished 
an act or consequence not wanted or desired and often unexpected

ungrudgingly.adverb
in a generous and ungrudging manner (he ungrudgingly agreed to pay for everybody's dinner when the guests found themselves without cash)

unknowing.adjective
not knowing; unaware
unknowingly.adverb

unknown.adjective
not known; unfamiliar (television was unknown in earlier times); not identified or ascertained (received flowers from an unknown admirer); not well known or widely known (an unknown artist) unknown.noun
a person or thing that is unknown (he is an unknown in this town)
unknowable.adjective
impossible to know, especially being beyond the range of human experience or understanding (the hitherto unknowable mysteries of the invisible world)
unknowability.or.unknowableness.noun
unknowably.adverb
unknowable.noun

unfamiliar.adjective
not being acquainted with; not conversant (unfamiliar with the roads here); not within one's knowledge; strange (unfamiliar faces)
unfamiliarly.adverb
unfamiliarity.noun.pronounced 'un fuh mil yare ity'

unwavering.adjective
if you describe a feeling or attitude as unwavering, you mean that it is strong and firm and does not weaken (she has been encouraged by the unwavering support of her family; his attitude was unwavering); not wavering; stedfast; steady
unwaveringly.adverb

unresolvable.adjective
not easily solved (the issue of peace versus war seems on the surface to be unresolvable and thus remains unsolved; insoluble; unsolvable; not capable of being resolved
unresolved.adjective
if a problem or difficulty is unresolved, no satisfactory.solution has been found to it (the issue remains of solving poverty for all humanity)

unsolvable.adjective
not easily solved or not able to be solved; insoluble; insolvable; irresoluble; irresolvable; unsoluble
unsolvability.noun,.plural.unsolvabilities

unsoluble.adjective
not easily solved

unleavened.adjective
made without yeast or any other leavening agent (unleavened bread)

urus.noun,.plural.uruses
an extinct wild ox, scientific name 'Bos primigenius', of Europe, northern Africa and western Asia, believed to be the ancestor of domestic cattle, also know as aurochs

unsuitable.adjective
not suitable; not appropriate (unsuitable attire is summer clothing used in a winter climate)
unsuitability.noun,.plural.unsuitabilities
unsuitableness.noun,.plural.unsuitablenesses
unsuitably.adverb
unsuited.adjective
if someone or something is unsuited to a particular job, situation or place, they do not have the right qualities or characteristics for it (he's unsuited for an outside job due to his injury; the snow cruiser proved hopelessly unsuited to Antarctic conditions); if two people are unsuited to each other, they have different personalities or interests and so are unlikely to have a successful relationship

unconcern.noun,.plural.unconcerns
lack of interest; indifference; lack of worry or apprehensiveness
unconcerned.adjective
not interested; indifferent; not anxious or not apprehensive; unworried
unconcernedly.adverb
unconcernedness.noun.(words ending in 'ess' are usually without pluralization - adding an 'es' making '...esses' is clumsy)

unworried.adjective
not worried or concerned; free of trouble and worry and care (the carefree joys of childhood; carefree millionaires)

unaware.adjective
not aware or cognizant
unaware, unawares.adverbs
by surprise; unexpectedly; without forethought or plan
unawarely.adverb
unawareness.noun,.plural.unawarenesses
Usage note: Unaware, followed by 'of' (expressed or implied), is the usual adjectival form modifying a noun or pronoun or following a linking verb (unaware of the difficulty, I went ahead; he was unaware of my presence); 'unawares' is the usual adverbial form (the rain caught them unawares meaning, without warning; they came upon it unawares meaning without design or plan). See more Usage notes

unintimidated.adjective
not intimidated; not shrinking from danger

unassuming.adjective
exhibiting no pretensions, boastfulness or ostentation; modest
unassumingly.adverb
unassumingness.noun.(normally used without being pluralized)

unworldly, unworldlier, unworldliest.adjectives
not of this world; spiritual; concerned with matters of the spirit or soul; not wise to the ways of the world; naive
unworldliness.noun.(normally used without being pluralized)

uncaused.adjective
existing without a perceptible cause; spontaneous

uncreated.adjective
not having been created; existing of itself; uncaused

uncastrated.adjective
not having been castrated

uncongenial.adjective
not congenial; if you describe a person or place as uncongenial, you mean that they are unfriendly and unpleasant (he continued to find the Simpsons uncongenial bores; it was an uncongenial place to work); not compatible or sympathetic, as in character; inconsistent; not appropriate; unsuitable; not pleasing; disagreeable
uncongeniality.noun,.plural.uncongenialities

unrestrained.adjective
not restrained, controlled or held in check; immoderate (unrestrained exploitation of natural resources); free of constraint; if you describe someone's behavior as unrestrained, you mean that it is extreme or intense, for example because they are expressing their feelings strongly or loudly (there was unrestrained joy on the faces of the people); spontaneous and natural (an unrestrained laugh) unrestrainedly.adverb
unrestrainedness.noun,.plural.unrestrainednesses

unassociated.adjective
not connected or associated

unlikely, unlikelier, unlikeliest.adjectives
not likely; improbable; if you say that something is unlikely to happen or unlikely to be true, you believe that it will not happen or that it is not true, although you are not completely sure; not promising; likely to fail
unlikeliness.noun.(normally used without being pluralized)
unlikeness.noun,.plural.unlikenesses
the quality or condition of being unlike; difference
unlikelihood.noun,.plural.unlikelihoods
the state of being unlikely or improbable; improbability; something unlikely
unlike.adjective
not alike; different (for twins, they are very unlike); not equal in some way or in various ways, as in amount
unlike.preposition
different from; not like (she's unlike the rest of her family; not typical of (it's unlike him not to call)

undisciplined.adjective
if you describe someone as undisciplined, you mean that they behave badly or in a disorganized way (a noisy and undisciplined group of kids); not subjected to discipline (undisciplined talent); not subjected to correction or discipline (let her children grow up uncorrected); lacking in discipline or control (undisciplined behavior)

unrelated.adjective
two things that are unrelated are not connected to each other in any way; if one thing is unrelated to another, there is no connection between them; you can also say that two things are unrelated (my line of work is entirely unrelated to politics); unconnected; if one person is unrelated to another, they are not members of the same family; you can also say that two people are unrelated; not associated; not connected by kinship (Jimmy is adopted and thus unrelated to Beth by blood; the two men look alike but are unrelated; dissimilar, unlike; unconnected; irrelevant; unassociated; incompatible

unconnected.adjective
not joined or connected; not coherent; disconnected (unconnected sentences)
unconnectedly.adverb
unconnectedness.noun.(normally used without being pluralized)

unsullied.adjective
not sullied; spotlessly clean and fresh (the unsullied snow of mountains); if something is unsullied, it has not been spoiled or made less pure by the addition of something unpleasant or unacceptable (she had the combined talents of toughness, intellect, experience and unsullied reputation; he smiled, unsullied by doubt)

utility.noun,.plural.utilities
the quality or condition of being useful; usefulness; a useful article or device; a publicly owned utility, such as electricity, water or public transportation, that is provided by the public utility providing the service) utility.adjective
used, serving or working in several capacities as needed; designed for various practical uses (a utility knife; a utility vehicle); raised or kept for the production of a farm product rather than for show or as pets (utility livestock); of the lowest grade (utility beef and chicken)

unsullied.adjective
if something is unsullied, it has not been spoiled or made less pure by the addition of something unpleasant or unacceptable (unsullied water; unsullied character); not sullied; not tainted; not tarnished; uncorrupted; uninjured; uncontaminated; undefiled; clean; pure; innocent

unaccounted.adjective
not taken into consideration or explained (she failed to get winter or all weather tires as she unaccounted for the snow on mountain roads this time of year; it's unaccounted for how the crop circle showed up)
unaccounted for.adjective
if people or things are unaccounted for, you do not know where they are or what has happened to them; not explained, understood or taken into account; missing or absent without explanation
unaccountable.adjective
impossible to account for; inexplicable (unaccountable absences; unaccountable errors); free from accountability; not responsible (government people acting unaccountably toward the public who elected them)
unaccountability.noun,.plural.unaccountabilities
unaccountableness.noun,.plural.unaccountablenesses
unaccountably.adverb

unprovable, unproved.adjectives
not provable (the theory of evolution after all these years remains both unproved and unprovable)

unapproved.adjective
not approved (there is little if any difference between an unapproved vaccine and an approved one as they both are are risky; an unapproved pesticide)

unscientific.adjective
not adhering to the principles of science; not knowledgeable about science or the scientific method
unscientifically.adverb

unclean, uncleaner, uncleanest.adjectives
foul or dirty; morally.defiled; unchaste; not clean
uncleanness.noun.(normally used without being pluralized)

undefiled.adjective
free from stain or blemish; immaculate; uncorrupted; chaste; clean, decent, immaculate, modest, pure, spotless, unblemished, unsullied

unspoiled, unspoilt.adjectives
if you describe a place as unspoiled, you think it is beautiful because it has not been changed or built on for a long time (the port is quiet and unspoiled; the unspoiled island of Cozumel off the coast of southeast Mexico near Cancun)