unhuman (adj.) Look up unhuman at Dictionary.com
1540s, "inhumane, cruel," from un- (1) "not" + human (adj.). Meaning "destitute of human qualities; superhuman" is from 1782.
unhygienic (adj.) Look up unhygienic at Dictionary.com
1883, from un- (1) "not" + hygenic.
uni- Look up uni- at Dictionary.com
word-forming element meaning "having one only," from Latin uni-, combining form of unus "one" (from PIE root *oi-no- "one, unique").
Uniate Look up Uniate at Dictionary.com
"pertaining to an Eastern Christian church that acknowledges the supremacy of the Pope," 1833, from Russian uniyat, from unia "unity, union," from Latin unus "one" (from PIE root *oi-no- "one, unique").
unicameral (adj.) Look up unicameral at Dictionary.com
1853, from uni- "one" + Late Latin camera "chamber" (see camera) + -al (1).
UNICEF Look up UNICEF at Dictionary.com
by 1948, acronym from United Nations International Children's Emergency Fund, which was created in 1946 (the name was changed 1953 to United Nations Children's Fund but the acronym endured).
unicellular (adj.) Look up unicellular at Dictionary.com
1858; see uni- + cellular.
unicorn (n.) Look up unicorn at Dictionary.com
early 13c., from Old French unicorne, from Late Latin unicornus (Vulgate), from noun use of Latin unicornis (adj.) "having one horn," from uni- "one" (from PIE root *oi-no- "one, unique") + cornus "horn," from PIE root *ker- (1) "horn; head."

The Late Latin word translates Greek monoceros, itself rendering Hebrew re'em (Deuteronomy xxxiii.17 and elsewhere), which probably was a kind of wild ox. According to Pliny, a creature with a horse's body, deer's head, elephant's feet, lion's tail, and one black horn two cubits long projecting from its forehead. Compare German Einhorn, Welsh ungorn, Breton uncorn, Old Church Slavonic ino-rogu.
unicycle (n.) Look up unicycle at Dictionary.com
1869, American English, from Latin uni- "one" (see uni-) + -cycle, from bicycle (from Greek kyklos "circle, wheel").
unidentifiable (adj.) Look up unidentifiable at Dictionary.com
1859, from un- + identifiable.
unidentified (adj.) Look up unidentified at Dictionary.com
1860, from un- (1) "not" + past participle of identify (v.).
unidirectional (adj.) Look up unidirectional at Dictionary.com
1883, from uni- + directional (see direction).
unification (n.) Look up unification at Dictionary.com
1849, noun of action from unify (v.). Unification Church was founded 1954.
uniform (adj.) Look up uniform at Dictionary.com
1530s, "of one form," from Middle French uniforme (14c.), from Latin uniformis "having only one form or shape," from uni- "one" (see uni-) + forma "form" (see form (n.)). Related: Uniformly.
uniform (n.) Look up uniform at Dictionary.com
"distinctive clothes worn by one group," 1748, from French uniforme, from the adjective (see uniform (adj.)).
uniform (v.) Look up uniform at Dictionary.com
1680s, "to make alike," from uniform (adj.). Meaning "to dress in a uniform" is from 1861. Related: Uniformed.
uniformitarian (n.) Look up uniformitarian at Dictionary.com
1840 in geology, from uniformity + -arian. Related: Uniformitarianism (1865).
uniformity (n.) Look up uniformity at Dictionary.com
early 15c., from Old French uniformite (14c.) or directly from Late Latin uniformitatem (nominative uniformitas) "uniformity," from Latin uniformis (see uniform (adj.)).
unify (v.) Look up unify at Dictionary.com
c. 1500, "to make into one," from Middle French unifier (14c.) or directly from Late Latin unificare "make one," from Latin uni- "one" (see uni-) + combining form of facere "to make" (from PIE root *dhe- "to set, put"). Related: Unified; unifying. Unified (field) theory in physics is recorded from 1935.
unilateral (adj.) Look up unilateral at Dictionary.com
1802, from Modern Latin unilateralis, from unum, neuter of unus "one" (from PIE root *oi-no- "one, unique") + latus (genitive lateralis) "the side, flank" (see latero-). Jeremy Bentham (1748-1832) may have been the first to use it in the legal sense of "made or entered into by one party." Related: Unilaterally. Unilateral disarmament is recorded from 1929.
It is useless for the sheep to pass resolutions in favor of vegetarianism, while the wolf remains of a different opinion. [William Ralph Inge, "Outspoken Essays," 1919]
unilateralism (n.) Look up unilateralism at Dictionary.com
1926, from unilateral + -ism. Earliest usages seem to be in the sense of "advocate of unilateral disarmament." Meaning "pursuit of a foreign policy without allies" is attested by 1964.
unimaginable (adj.) Look up unimaginable at Dictionary.com
1610s, from un- (1) "not" + imaginable. Related: Unimaginably.
unimaginative (adj.) Look up unimaginative at Dictionary.com
1802, from un- (1) "not" + imaginative.
unimpaired (adj.) Look up unimpaired at Dictionary.com
1580s, from un- (1) "not" + past participle of impair (v.). Rare before c. 1760.
unimpeachable (adj.) Look up unimpeachable at Dictionary.com
1784, from un- (1) "not" + impeachable. Related: Unimpeachably.
unimpeded (adj.) Look up unimpeded at Dictionary.com
1760, from un- (1) "not" + past participle of impede (v.).
unimportance (n.) Look up unimportance at Dictionary.com
1751; see unimportant + -ance.
unimportant (adj.) Look up unimportant at Dictionary.com
1750, from un- (1) "not" + important (adj.). Used earlier in a sense of "unassuming, modest" (1727). Related: Unimportantly.
unimposing (adj.) Look up unimposing at Dictionary.com
"unimpressive," 1809, from un- (1) "not" + imposing.
unimpressed (adj.) Look up unimpressed at Dictionary.com
1861, "not awed," from un- (1) "not" + past participle of impress (v.). Used earlier in a sense of "not subjected to restraint" (1743). Unimpressive is recorded from 1796.
unimproved (adj.) Look up unimproved at Dictionary.com
1660s, "not made better," from un- (1) "not" + past participle of improve (v.). Sense of "not developed or taken advantage of" (of land) is recorded from 1781.
unincorporated (adj.) Look up unincorporated at Dictionary.com
1715, from un- (1) "not" + past participle of incorporate (v.).
uninflected (adj.) Look up uninflected at Dictionary.com
1713, from un- (1) "not" + past participle of inflect (v.).
uninfluenced (adj.) Look up uninfluenced at Dictionary.com
1734, from un- (1) "not" + past participle of influence (v.).
uninformed (adj.) Look up uninformed at Dictionary.com
1590s, from un- (1) "not" + past participle of inform. Originally in reference to some specific matter or subject; general sense of "uneducated, ignorant" is recorded from 1640s.
uninhabitable (adj.) Look up uninhabitable at Dictionary.com
mid-15c., from un- (1) "not" + inhabitable.
uninhabited (adj.) Look up uninhabited at Dictionary.com
1570s, from un- (1) "not" + past participle of inhabit (v.).
uninhibited (adj.) Look up uninhibited at Dictionary.com
1880, from un- (1) "not" + past participle of inhibit.
uninitiated (adj.) Look up uninitiated at Dictionary.com
1670s, from un- (1) "not" + past participle of initiate (v.).
uninjured (adj.) Look up uninjured at Dictionary.com
1570s, from un- (1) "not" + past participle of injure (v.).
uninquisitive (adj.) Look up uninquisitive at Dictionary.com
c. 1600, from un- (1) "not" + inquisitive.
uninspired (adj.) Look up uninspired at Dictionary.com
1680s, from un- (1) "not" + inspired.
unintelligent (adj.) Look up unintelligent at Dictionary.com
c. 1600, from un- (1) "not" + intelligent (adj.). Related: Unintelligently.
unintelligible (adj.) Look up unintelligible at Dictionary.com
1610s, "incapable of being understood," from un- (1) "not" + intelligible. Related: Unintelligibly.
unintended (adj.) Look up unintended at Dictionary.com
1640s, from un- (1) "not" + past participle of intend (v.).
unintentional (adj.) Look up unintentional at Dictionary.com
1701, from un- (1) "not" + intentional (adj.). Related: Unintentionally.
uninterested (adj.) Look up uninterested at Dictionary.com
1640s, "unbiased," from un- (1) "not" + past participle of interest (v.). It later meant "disinterested" (1660s); sense of "unconcerned, indifferent" is recorded from 1771. This is the correct word for what often is miscalled disinterested.
uninteresting (adj.) Look up uninteresting at Dictionary.com
"not capable of exciting interest," 1769, from un- (1) "not" + interesting.
uninterrupted (adj.) Look up uninterrupted at Dictionary.com
c. 1600, "continuous;" 1650s, "undisturbed," from un- (1) "not" + past participle of interrupt. Related: Uninterruptedly.
uninvite (v.) Look up uninvite at Dictionary.com
"countermand an invitation," 1660s, from un- (2) "opposite of" + invite (v.). Related: Uninvited; uninviting.