unsung (adj.) Look up unsung at Dictionary.com
early 15c., "not uttered in a song," from un- (1) "not" + past participle of sing (v.). Similar formation in German ungesungen. Meaning "not celebrated" is recorded from 1660s.
unsupervised (adj.) Look up unsupervised at Dictionary.com
1845, from un- (1) "not" + past participle of supervise (v.).
unsure (adj.) Look up unsure at Dictionary.com
c. 1400, "not safe against attack," also "lacking certainty," from un- (1) "not" + sure (adj.).
unsuspected (adj.) Look up unsuspected at Dictionary.com
1520s, from un- (1) "not" + past participle of suspect (v.).
untainted (adj.) Look up untainted at Dictionary.com
1580s, in the moral sense; c. 1600 in the physical sense; from un- (1) "not" + past participle of taint (v.). Earlier was untained (mid-15c.), from a Middle English variant of taint (v.).
untamed (adj.) Look up untamed at Dictionary.com
mid-14c., from un- (1) "not" + past participle of tame (v.). Similar formation in Old English untemed, Old Norse utamdr, Old High German ungizamot.
untangle (v.) Look up untangle at Dictionary.com
1540s, from un- (2) "reverse, opposite of" + tangle (v.). Related: Untangled; untangling.
untempered (adj.) Look up untempered at Dictionary.com
mid-15c., "not properly mixed, undiluted," from un- (1) "not" + past participle of temper (v.). Similar formation in Middle Dutch ongetempert, Middle High German ungetempert. Earlier as "unrestrained" (late 14c.), also, of a musical instrument, "not properly tuned;" meaning "unhardened" is from 1820.
untenable (adj.) Look up untenable at Dictionary.com
1640s, "indefensible, incapable of being held against attack," from un- (1) "not" + tenable (adj.). Figurative sense is recorded from 1690s.
unthinkable (adj.) Look up unthinkable at Dictionary.com
early 15c., "too large to be conceived, unimaginable," from un- (1) "not" + think (v.) + -able. Meaning "incapable of being framed by thought" is recorded from mid-15c.
untidy (adj.) Look up untidy at Dictionary.com
early 13c., "untimely, unseasonable, unsuitable," from un- (1) "not" + tidy (adj.). Similar formation in West Frisian ontidich, Middle Dutch ontidich, Dutch ontijdig, Old High German unzitich, German unzeitig, Norwegian utidig "untimely, unseasonable, unfavorable." Meaning "poorly cared for, not neat" is recorded from mid-14c.
untie (v.) Look up untie at Dictionary.com
Old English untigan "loosen, unchain," from un- (2) "opposite of" + tie (v.). Related: Untied; untying.
until (prep.) Look up until at Dictionary.com
c. 1200, from till (prep.). The first element is un- "as far as, up to" (also in unto), from Old Norse *und "as far as, up to," from Proto-Germanic *und- (source also of Old English "up to, as far as," Old Frisian, Old Saxon, Gothic und), from PIE *nti-, from root *ant- "front, forehead" (see ante).

The two syllables have the same meaning. Originally also used of persons and places. As a conjunction from c. 1300. Similar formation in Swedish intill, Danish indtil (northern English and Scottish formerly also had intill/intil "into, in"). The Modern German equivalent, bis (Old High German biaz), is a similar compound, of Old High German bi "by, at, to" and zu "to."
untimely (adj.) Look up untimely at Dictionary.com
1530s, "coming before the proper or usual time," from un- (1) "not" + timely (adj.). Similar formation in Middle Danish utimelig, of weather, etc. Old English had untidlic "unseasonable." Related: Untimeliness.
unto (prep.) Look up unto at Dictionary.com
mid-13c., perhaps a modification of until, with southern to in place of northern equivalent till. Or perhaps a contraction of native *und to, formed on the model of until from Old English *un- "up to, as far as," cognate of the first element in until. "Very rare in standard writers of the 18th c.," according to OED, and since then chiefly in dignified, archaic, or Biblical styles.
untold (adj.) Look up untold at Dictionary.com
Old English unteald, "not counted or reckoned," from un- (1) "not" + past participle of tell (v.) in its original numerical sense. Similar formation in Middle Dutch ongetellet, German ungezahlt, Old Norse utaliðr. Meaning "not related or recounted" is recorded from late 14c.
untouchable (adj.) Look up untouchable at Dictionary.com
1560s, "immaterial," from un- (1) "not" + touchable (see touch (v.)). Meaning "that legally cannot be interfered with" is recorded from 1734. Meaning "too loathsome or defiling to be touched" is recorded from 1873. The noun, in reference to a hereditary low caste of India, is attested from 1909; the term and the restrictions were made illegal in India in 1947.
untoward (adj.) Look up untoward at Dictionary.com
1520s, "not having inclination" (to or for something), also "difficult to manage, unruly," from un- (1) "not" + toward (adj.).
untried (adj.) Look up untried at Dictionary.com
1510s, "not proven or tested," from un- (1) "not" + tried.
untrodden (adj.) Look up untrodden at Dictionary.com
c. 1300, from un- (1) "not" + past participle of tread (v.).
untroubled (adj.) Look up untroubled at Dictionary.com
late 15c., from un- (1) "not" + past participle of trouble (v.).
untrue (adj.) Look up untrue at Dictionary.com
Old English untreowe "unfaithful" (of persons), from un- (1) "not" + true (adj.). Similar formation in Middle Dutch ongetrouwe, Middle Low German ungetruwe, Old High German ungitriuwi, Old Norse utryggr. Meaning "contrary to facts" is attested from c. 1300.
untrustworthy (adj.) Look up untrustworthy at Dictionary.com
1846, from un- (1) "not" + trustworthy. Related: Untrustworthiness.
untruth (n.) Look up untruth at Dictionary.com
Old English untreowþ "unfaithfulness, treachery," from un- (1) "not" + truth (n.). Similar formation in Old Norse utrygð. Meaning "falsehood" is attested from mid-15c., as is that of "a lie." Related: Untruthful.
unused (adj.) Look up unused at Dictionary.com
c. 1300, "unaccustomed," from un- (1) "not" + past participle of use (v.). Meaning "not employed" is recorded from late 14c.
unusual (adj.) Look up unusual at Dictionary.com
1580s, from un- (1) "not" + usual (adj.). Related: Unusually.
unvarnished (adj.) Look up unvarnished at Dictionary.com
c. 1600, of statements, "not embellished," from un- (1) "not" + past participle of varnish (v.). Literal sense of "not covered in varnish" is recorded from 1758.
unveil (v.) Look up unveil at Dictionary.com
1590s, in reference to sight, "to make clear," from un- (2) "opposite of" + veil (v.). Sense of "to display or reveal" (something) is from 1650s. Related: Unveiled; unveiling.
unwanted (adj.) Look up unwanted at Dictionary.com
1690s, from un- (1) "not" + past participle of want (v.).
unwarranted (adj.) Look up unwarranted at Dictionary.com
1570s, from un- (1) "not" + past participle of warrant (v.).
unwashed (adj.) Look up unwashed at Dictionary.com
late 14c., from un- (1) "not" + past participle of wash (v.). Replaced Middle English unwashen, from Old English unwæscen. Noun sense of "the lower class" is attested from 1830.
unwearied (adj.) Look up unwearied at Dictionary.com
mid-13c., from Old English ungewerigod, from un- (1) "not" + past participle of weary (v.).
unwed (adj.) Look up unwed at Dictionary.com
1510s, from un- (1) "not" + past participle of wed (v.). Unwedded "unmarried; celibate" is from c. 1200.
unwelcome (adj.) Look up unwelcome at Dictionary.com
early 14c., from un- (1) "not" + welcome (adj.). Similar formation in Middle Dutch onwillecome, German unwillkommen.
unwell (adj.) Look up unwell at Dictionary.com
mid-15c., "somewhat ill," from un- (1) "not" + well (adj.). Similar formation in North Frisian unwel, German unwohl.
unwholesome (adj.) Look up unwholesome at Dictionary.com
c. 1200, from un- (1) "not" + wholesome (adj.). Similar formation in Flemish onheylsaem, German unheilsam, Old Norse uheilsamr.
unwieldy (adj.) Look up unwieldy at Dictionary.com
late 14c., "lacking strength, powerless," from un- (1) "not" + obsolete wieldy, from Old English wielde "active, vigorous," from Proto-Germanic *walth- "have power" (see wield (v.)). Meaning "moving ungracefully" is recorded from 1520s; in reference to weapons, "difficult to handle, awkward by virtue of size or shape" it is attested from 1540s. Related: Unwieldiness.
unwilling (adj.) Look up unwilling at Dictionary.com
early 15c., altered from or re-formed to replace Middle English unwilland, from Old English unwillende; see un- (1) "not" + willing (adj.); see -ing (2). Related: Unwillingly; unwillingness.
unwind (v.) Look up unwind at Dictionary.com
early 14c., "to undo" (a bandage, wrapping, etc.), from un- (2) "opposite of" + wind (v.1). Similar formation in Old English unwindan "unveil, uncover," Dutch ontwinden, Old High German intwindan. Reflexive sense is recorded from 1740; figurative sense of "to release oneself from tensions, to relax" is by 1938. Related: Unwound; unwinding.
unwise (adj.) Look up unwise at Dictionary.com
Old English unwis, from un- (1) "not" + wise (adj.). Similar formation in Middle Dutch onwijs, Old High German unwis, German unweise, Old Norse uviss, Gothic unweis.
unwitting (adj.) Look up unwitting at Dictionary.com
late 14c., altered from or re-formed to replace unwitand, from Old English unwitende "ignorant," from un- (1) "not" + witting (adj.); see -ing (2). Similar formation in Old High German unwizzanti, German unwissend, Old Norse uvitandi, Gothic unwitands. Rare after c. 1600; revived c. 1800. Related: Unwittingly.
unwonted (adj.) Look up unwonted at Dictionary.com
"not usual," 1550s, from un- (1) "not" + wonted. Earlier (and more correctly) unwont (c. 1400).
unworthy (adj.) Look up unworthy at Dictionary.com
mid-13c., unwurði, from un- (1) "not" + worthy (adj.). Similar formation in Middle Dutch onwerdich, Dutch onwaardig, Middle Low German unwerdich, Old High German unwirdig, Old Norse uverðugr. Old English had unweorðlic. Related: Unworthiness.
unwrap (v.) Look up unwrap at Dictionary.com
late 14c., from un- (2) "opposite of" + wrap (v.). Related: Unwrapped; unwrapping.
unwritten (adj.) Look up unwritten at Dictionary.com
mid-14c., from un- (1) "not" + past participle of write (v.). Similar formation in Old English unwriten, Old Norse uritinn.
unyielding (adj.) Look up unyielding at Dictionary.com
1590s of persons; 1650s, of substances; from un- (1) "not" + yielding (see yield (v.)).
unzip (v.) Look up unzip at Dictionary.com
1939, from un- (2) "opposite of" + zip (v.). Related: Unzipped; unzipping.
up (adv.) Look up up at Dictionary.com
Old English up, uppe, from Proto-Germanic *upp- "up" (source also of Old Frisian, Old Saxon up "up, upward," Old Norse upp; Danish, Dutch op; Old High German uf, German auf "up"; Gothic iup "up, upward," uf "on, upon, under;" Old High German oba, German ob "over, above, on, upon"), from PIE root *upo "up from below" (source also of Sanskrit upa "near, under, up to, on," Greek hypo "under, below," Latin sub "under;" see sub-).

As a preposition, "to a higher place" from c. 1500; also "along, through" (1510s), "toward" (1590s). Often used elliptically for go up, come up, rise up, etc. Up the river "in jail" first recorded 1891, originally in reference to Sing Sing, which is up the Hudson from New York City. To drive someone up the wall (1951) is from the notion of the behavior of lunatics or caged animals. Insulting retort up yours (scil. ass) attested by late 19c.
up (v.) Look up up at Dictionary.com
1550s, "to drive and catch (swans)," from up (adv.). Intransitive meaning "get up, rise to one's feet" (as in up and leave) is recorded from 1640s. Sense of "to move upward" is recorded from 1737. Meaning "increase" (as in up the price of oil) is attested from 1915. Compare Old English verb uppian "to rise up, swell." Related: Upped; upping. Upping block, used for mounting or dismounting horses, carriages, etc., is attested from 1796 (earlier was horsing-block, 1660s).
up- Look up up- at Dictionary.com
prefix with various senses, from Old English up (adv.), corresponding to similar prefixes in other Germanic languages.