unproductive.adjective
not productive; idle; nothing added to exchangeable value unproductively.adverb
unproductiveness.noun

undertake, undertook, undertaken, undertaking, undertakes.verbs
transitive verb use.to take upon oneself; decide or agree to do (undertake a task); to pledge or commit oneself to (undertake oneself to care for an elderly relative); to set about; begin
intransitive verb use.to make oneself responsible

unambiguous.adjective
having or exhibiting no ambiguity or uncertainty; clear; accurate
unambiguously.adverb

unequivocal.adjective
admitting of no doubt or misunderstanding; clear and unambiguous (an unequivocal success)
unequivocally.adverb

useless.adjective
being or having no beneficial use; futile or ineffective; incapable of functioning or assisting; ineffectual (she panics easily and is useless in an emergency)
uselessly.adverb
uselessness.noun

useful.adjective
having a beneficial use; serviceable (a useful kitchen gadget); having practical.utility (a useful service to othes)
usefully.adverb
usefulness.noun

use, used, using, uses.verbs
transitive verb use.to put into service or apply for a purpose; employ; to avail oneself of; practice (use caution when driving on snowy, icy roads); to conduct oneself toward; treat or handle; to seek or achieve an end by means of; exploit (used their highly placed friends to gain access to the position); to take or consume; partake of (she rarely used alcohol)
intransitive verb use.used in the past tense followed by 'to' in order to indicate a former.state, habitual.practice or custom (mail service used to be faster)
use.noun
the act of using; the application or employment of something for a purpose (with the use of a calculator; skilled in the use of the bow and arrow); the condition or fact of being used (a chair in regular use); the manner of using; usage (learned the proper use of power tools); the permission, privilege or benefit of using something (gave us the use of their summerhouse); the power or ability to use something (lost the temporary use of her vehicle while it needed servicing); the need or occasion to use or employ (have no use for these old clothes); the quality of being suitable or adaptable to an end; usefulness (tried to be of use in the kitchen); a purpose for which something is used (a tool with several uses; a pretty bowl, but of what use is it?); gain or advantage; good (what's the use in talking to them about it? they listen, but never help); accustomed or usual procedure or practice; the benefit or profit of lands and tenements of which the legal title and possession are vested in another; the arrangement establishing the equitable right to such benefits and profits
used to.phrasal verb
if something used to happen, it happened regularly or all the time in the past, but does not happen now (he used to go to our school; we're eating out more often than we used to; you didn't use to eat chips when you were younger)
use up.phrasal verb
to consume completely (the world is using up resources)
usable.also.useable.adjective
that can be used (recyclables are usable); fit for use; convenient to use (usable spare parts; a usable reference book)
usability.or.usableness.noun
usably.adverb

usage.noun,.plural.usages
the act, manner or amount of using; use (the usage of a technical term; an instrument such as a meter that measures water usage); the act or manner of treating; treatment (subjected the car to rough usage by driving on a potholed gravel road); a usual, habitual or accepted.practice; a habit; the way in which words or phrases are actually used, spoken or written in a speech community (the Spanish speech community has a different way of speaking when compared to English)

unswerving.adjective
not veering or turning aside (walked a straight path); constant; steady (unswerving allegiance; unswerving devotion); not swerving
unswervingly.adverb

undeviating.adjective
keeping a true course; unswerving (served his family with undeviating loyalty and devotion); not deviating
undeviatingly.adverb

unreceptive.adjective
not receptive

unreasonable.adjective
not governed by reason (an unreasonable request for more taxes); exceeding reasonable limits; immoderate (unreasonable demands; "The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man."....George Bernard Shaw, Irish Writer and Playwright)
unreasonably.adverb
unreasonableness.noun
unreasoning.adjective
not governed or moderated by reason
unreasoningly.adverb

unruly, unrulier, unruliest.adjectives
disorderly; acting without commonsense; difficult or impossible to discipline, control or rule (the little kid was described as refusing control of those trying to vaccinate him as he had direct and authoritative information from his mother that vaccines can be injurious); if you describe someone as unruly, you mean that they behave badly and are difficult to impossible to reason with for change and maybe for good reason; violent; wild; intractable; refractory; recalcitrant
unruliness.noun

unfeigned.adjective
not feigned; genuine in feeling; sincere; not a phony; unfeigned stresses.spontaneity and absence of pretense (her unfeigned delight at receiving the award)
unfeignedly.adverb

undeniable.adjective
difficult or impossible to deny; irrefutable (undeniable facts) undeniably.adverb
undeniableness.noun

unorthodox.adjective
breaking with convention or tradition; not orthodox
unorthodoxly.adverb
unorthodoxy.noun

unabated.adjective
sustaining an original intensity or maintaining full force with no decrease (an unabated windstorm; once blessings start they continue unabatedly)
unabatedly.adverb

utility.noun,.plural.utilities
the quality or condition of being useful; usefulness; a useful article or device (kitchens have many gadget devices which are useful); a public utility such as transportation, water, gas and electricity
utility.adjective
used, serving or working in several capacities as needed, especially (a utility cast member is prepared to play any of the smaller theatrical roles on short notice; capable of playing as a substitute in any of several positions (a utility infielder such as in baseball); designed for various often heavy-duty 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, utility chickens)

uncultured.adjective
not cultured or cultivated (an uncultured coal-mining town; regarded him as an uncultured brute); lacking art or knowledge; if you describe someone as uncultured, you are critical of them because they do not seem to know much about art, literature and other cultural topics

unrefined.adjective
in its natural state; an unrefined food or other substance is in its natural state and has not been processed (unrefined carbohydrates include brown rice and other grains; unrefined petroleum is called crude oil); the word 'unrefined' is also used of men and women's behaviors; not refined; crude; uncouth (how can a seemingly refined girl be drawn to such an unrefined man?)

uncivilized.adjective
not civilized; barbarous
uncivilizedly.adverb
uncivilizedness.noun

uncivil.adjective
discourteous; rude; uncivilized; barbarous
uncivilly.adverb
uncivilness.noun

unconditional.adjective
without conditions or limitations; absolute (had carte blanche approval)
unconditionally.adverb
unconditionality.or.unconditionalness.noun

unconditioned.adjective
unconditional; unrestricted; in psychology, not dependent on or resulting from conditioning; unlearned or natural
unconditionedness.noun
unconditioned response.noun,.plural.unconditioned responses
in psychology, a natural, usually unvarying response evoked by a stimulus in the absence of learning or conditioning
unconditioned stimulus.noun,.plural.unconditioned stimuli
in psychology, a stimulus that evokes an unconditioned response

unstinting.adjective
bestowed liberally (unstinting approval)
unstintingly.adverb

unsettle, unsettled, unsettling, unsettles.verbs
transitive verb use.to displace from a settled.condition; disrupt; to make uneasy; disturb
intransitive verb use.to become unsettled
unsettlingly.adverb
unsettlement.noun

unachievable.adjective
impossible to achieve or attain (an seemingly unachievable goal)

unbounded.adjective
having no boundaries or limits (unbounded space); not kept within bounds; unrestrained (unbounded enthusiasm)
unboundedly.adverb
unboundedness.noun

uncomfortable.adjective
unable to be comfortable; to experience physical discomfort; ill at ease; uneasy; feeling and/or causing anxiety; disquieting
uncomfortably.adverb
uncomfortableness.noun

unchaste, unchaster, unchastest.adjectives
not chaste or modest
unchastely.adverb
unchasteness.or.unchastity.noun

unquenchable.adjective
impossible to satisfy (unquenchable thirst); impossible to suppress or destroy (unquenchable enthusiasm)
unquenchably.adverb

underlying.adjective
lying under or beneath something (underlying strata); basic; fundamental; present but not obvious; implicit (an underlying meaning); taking precedence; prior (she had an underlying concern for her daughters on vacation).
underlie, underlay, underlain, underlying, underlies
to be located under or below; to be the support or basis of; account for (many factors underlay her decision to stay put)

underneath.adverb
in or to a place beneath; below; on the lower face or underside underneath.preposition
under; below; beneath
underneath.adjective
lower; under
underneath.noun
the part or side below or under

unarticulated.adjective
not articulated; not carefully or thoroughly thought out; in biology, not having joints or segments