Online Etymology Dictionary

untie (v.): Old English untiegan, from un- (2) + tie (v.). Related: Untied; untying.
until: c.1200, from Old Norse und "as far as, up to" (related to Old English end; see end) + till "until, up to" (see till). Originally also used of persons and places. Cf. Swedish intill, Danish indtil. 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.): 1530s, "coming before the proper or usual time," from un- (1) "not" + timely. Cf. Middle Danish utimelig, of weather, etc.
untitled (adj.): 1610s, "unnamed," from un- (1) "not" + past participle of title (v.). Meaning "having no right" is from 1660s; that of "undistinguished" is from 1798.
unto: mid-13c., perhaps a modification of until, with southern to in place of northern equivalent till. Or perhaps a native formation on the model of until from Old English *und- "up to," cognate of the first element in until. Since 18c., chiefly in dignified, archaic, or Biblical styles.
untold (adj.): Old English unteald, "not counted or reckoned," from un- (1) "not" + past participle of tell in its original numerical sense. Cf. Middle Dutch ongetellet, German ungezahlt, Old Norse utaliðr. Meaning "not related or recounted" is recorded from late 14c.
untouchable (adj.): 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.
untouched (adj.): late 14c., from un- (1) "not" + past participle of touch (v.).
untoward (adj.): 1520s, "not having inclination" (to or for something), also "difficult to manage, unruly," from un- (1) "not" + toward.
untrammeled (adj.): also untrammelled, 1795, from un- (1) "not" + past participle of trammel.
untried (adj.): 1510s, "not proven or tested," from un- (1) "not" + past participle of try.
untrodden (adj.): c.1300, from un- (1) "not" + past participle of tread (v.).
untroubled (adj.): late 15c., from un- (1) "not" + past participle of trouble (v.).
untrue (adj.): Old English untreowe "unfaithful" (of persons), from un- (1) "not" + true (adj.). Cf. 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.): 1846, from un- (1) "not" + trustworthy.
untruth (n.): Old English untreowþ "unfaithfulness," from un- (1) "not" + truth. Cf. Old Norse utrygð. Meaning "falsehood" is attested from mid-15c., as is that of "a lie."
unusable (adj.): 1825, from un- (1) "not" + usable.
unused (adj.): c.1300, "unaccustomed," from un- (1) "not" + past participle of use (v.). Meaning "not employed" is recorded from late 14c.
unusual (adj.): 1580s, from un- (1) "not" + usual. Related: Unusually.
unutterable (adj.): 1580s, from un- (1) "not" + utterable (see utter (v.)). As a noun, from 1788; unutterables as a euphemism for "trousers" is recorded by 1843.
unvanquished (adj.): late 14c., from un- (1) "not" + past participle of vanquish.
unvarnished (adj.): 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.): 1590s, in reference to sight, "to make clear," from un- (2) + veil (v.). Sense of "to display or reveal" (something) is from 1650s. Related: Unveiled; unveiling.
unwanted (adj.): 1690s, from un- (1) "not" + past participle of want (v.).
unwarranted (adj.): 1570s, from un- (1) "not" + past participle of warrant (v.).
unwary (adj.): 1570s, from un- (1) "not" + wary.
unwashed (adj.): late 14c., from un- (1) "not" + past participle of wash (v.). Noun sense of "the lower class" is attested from 1830.
unwavering (adj.): 1560s, from un- (1) "not" + present participle of waver.
unwearied (adj.): Old English ungewerigod, from un- (1) "not" + past participle of weary.
unwed (adj.): 1510s, from un- (1) "not" + past participle of wed.
unwelcome (adj.): early 14c., from un- (1) "not" + welcome (adj.). Cf. Middle Dutch onwillecome, German unwillkommen.
unwell (adj.): mid-15c., "somewhat ill," from un- (1) "not" + well (adj.). Cf. North Frisian unwel, German unwohl.
unwholesome (adj.): c.1200, from un- (1) "not" + wholesome. Cf. Flemish onheylsaem, German unheilsam, Old Norse uheilsamr.
unwieldy (adj.): late 14c., "lacking strength," from un- (1) "not" + Old English wielde "active, vigorous," from Proto-Germanic *walth- "have power" (see wield). 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.
unwilling (adj.): Old English unwillende, from un- (1) "not" + willing. Re-formed 16c. Related: Unwillingly; unwillingness.
unwind (v.): early 14c., "to undo" (a bandage, wrapping, etc.), from un- (2) + wind (v.). Cf. Old English unwindan, Dutch ontwinden, Old High German intwindan. Refl. sense is recorded from 1740; figurative sense of "to release oneself from tensions, to relax" is recorded from 1938. Related: Unwound; unwinding.
unwise (adj.): Old English unwis, from un- (1) "not" + wise (adj.). Cf. Middle Dutch onwijs, Old High German unwis, German unweise, Old Norse uviss, Gothic unweis.
unwisely (adv.): Old English unwislice; see unwise + -ly (2).
unwitting (adj.): Old English unwitende, from un- (1) "not" + witting. Cf. Old High German unwizzanti, German unwissend, Old Norse uvitandi, Gothic unwitands. Rare after c.1600; revived c.1800.
unwonted (adj.): "not usual," 1550s, from un- (1) "not" + past participle of wont.
unworldly (adj.): 1707, from un- (1) "not" + worldly.
unworthy (adj.): mid-13c., unwurði, from un- (1) "not" + worthy. Cf. Middle Dutch onwerdich, Dutch onwaardig, Middle Low German unwerdich, Old High German unwirdig, Old Norse uverðugr.
unwrap (v.): late 14c., from un- (2) + wrap. Related: Unwrapped; unwrapping.
unwritten (adj.): mid-14c., from un- (1) "not" + past participle of write (v.). Cf. Old English unwriten, Old Norse uritinn.
unyielding (adj.): 1590s of persons; 1650s, of substances; from un- (1) "not" + yielding (see yield (v.)).
unzip (v.): 1939, from un- (2) + zip (v.). Related: Unzipped; unzipping.
up (adv.): Old English up, uppe, from Proto-Germanic *upp- "up" (cf. Old Frisian up; Old Norse upp; Danish, Dutch op; Old High German uf, German auf "up"; Gothic iup "up, upward," uf "on, upon, under;" OHG oba, German ob "over, above, on, upon"), from PIE root *upo "up from below" (cf. Sanskrit upa "near, under, up to, on," Greek hypo "under, below," Latin sub "under;" see sub-).

Meaning "exhilarated, happy" first attested 1815. Musical up tempo (adj.) is recorded from 1948. Up-and-coming "promising" is from 1848. Phrase on the up-(and-up) "honest, straightforward" first attested 1863, American English. 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.): earliest recorded sense is "to drive and catch (swans)," 1560, from up (adv.). Meaning "to get up, rise to one's feet" (as in up and leave) is recorded from 1643. Sense of "to move upward" is recorded from 1737. Meaning "increase" (as in up the price of oil) is attested from 1915. Cf. Old English verb uppian "to rise." Upping block is attested from 1796.
up-: prefix with various senses, from Old English up (see up (adv.)), corresponding to similar prefixes in other Germanic languages.
up-river: 1774, from up + river.