unobservable.adjective
not accessible to direct.observation; imperceptible
unobserved.adjective
if you do something unobserved, you do it without being seen by other people
unobserving.adjective
inattentive

uncharted.adjective
not charted or recorded on a map or plan (uncharted waterways; uncharted desert; the uncharted wilderness); the unknown

unending.adjective
having or seeming to have no end; countless or continual (the vast.multiverse is unending)

uncomplicated.adjective
not complex or involved in many pursuits; simple (found an uncomplicated solution to a problem)

unstoppable.adjective
difficult or impossible to preclude or stop ("This movement toward freedom is natural and unstoppable and good."....Pauline Kael
unstoppably.adverb

uninformed.adjective
not having, showing or making use of information; not informed (uninformed voters who vote not with any critical thinking {questions}, but with the zeitgeist; an uninformed decision)

unsure.adjective
lacking.confidence; not fixed or certain in mind about something, thus.requiring more information on one's point of consideration
unsurely.adverb
unsureness.noun,.plural.unsurenesses

underdog.noun,.plural.underdogs
one others regard as not being important; ineffective; one that is seems to be at a disadvantage

UNESCO, is an acronym for United Nations Educational, Scientific and Cultural Organization (some parts of the UN {United Nations} are or were good)

URL.abbreviation
the acronym URL stands for Uniform (or universal) Resource Locator, which is the address of a World Wide Web page, beginning usually with https://

undignified.adjective
lacking in or damaging to dignity