A- (3) prefix meaning "not," from Gk a-, an- "not," from pie base *ne "not" (see un-)

unilateral --- 1802, from Mod.L. unilateralis, from unum, neut. of unus "one" (see one) + latus (gen. lateralis) "side" (see oblate (n.)). Jeremy Bentham (1748-1832) may have been the first to use it in the legal sense of "made or entered into by one party." Unilateral disarmament is recorded from 1929. Unilateralism is recorded from 1926, and seems to have been used in the sense of "advocate of unilateral disarmament." Meaning "pursuit of a foreign policy without allies" is attested from 1964.

unimpaired --- 1583, from un- (1) "not" + pp. of impair. Rare before c.1760.

unimpeachable --- 1784, from un- (1) "not" + impeach (v.) + -able.

unimpeded --- 1760, from un- (1) "not" + pp. of impede.

unimportant --- 1750, from un- (1) "not" + important. Used earlier in a sense of "unassuming, modest" (1727).

unimpressed --- 1861, "not awed," from un- (1) "not" + pp. of impress. Used earlier in a sense of "not subjected to restraint" (1743). Unimpressive is recorded from 1796.

unimproved --- 1665, "not made better," from un- (1) "not" + pp. of improve. Sense of "not developed or taken advantage of" is recorded from 1781.

uninformed --- 1597, from un- (1) "not" + pp. of inform. Originally in ref. to some specific matter or subject; general sense of "uneducated, ignorant" is recorded from 1647.

uninhabitable --- 1448, from un- (1) "not" + inhabit (v.) + -able. Uninhabited is attested from 1571.

uninhibited --- 1880, from un- (1) "not" + pp. of inhibit.

unintelligible --- 1616, "incapable of being understood," from un- (1) "not" + intelligible.

uninterested --- c.1646, "unbiased," from un- (1) "not" + pp. of interest. It later meant "disinterested" (1661); sense of "unconcerned, indifferent" is recorded from 1771. This is the correct word for what often is miscalled disinterested.

uninterrupted --- 1602, from un- (1) "not" + pp. of interrupt.

uninvited --- 1631, from un- (1) "not" + pp. of invite. Uninviting is recorded from 1686.

union --- 1410, "action of joining one thing to another," from O.Fr. union (12c.), from L.L. unionem (nom. unio) "oneness, unity, a uniting," also in L. meaning "a single pearl or onion," from unus "one," from PIE *oinos (see one). Sense of "action of uniting into one political body" is attested from 1547. Meaning "group of people or states" is from 1660. Short for trade union, it is recorded from 1833. U.S. political sense is attested from 1775; used especially during the Civil War, in ref. to the remainder of the United States after the Southern secession. Unionize "make into a union" is attested from 1841.

Union Jack --- 1674, from union + jack (n.); properly a small British union flag flown as the jack of a ship, but it has long been in use as a general name for the union flag. The Union flag (1634) was introduced to symbolize the union of the crowns of England and Scotland (in 1603) and was formed of a combination of the cross saltire of St. Andrew and the cross of St. George. The cross saltire of St. Patrick was added 1801 upon the union of parliaments of Great Britain and Ireland.

unique --- 1602, "single, solitary," from Fr. unique, from L. unicus "single, sole," from unus "one" (see one). Meaning "forming the only one of its kind" is attested from 1618; erroneous sense of "remarkable, uncommon" is attested from mid-19c.

unisex --- sexually indistinguishable or neutral, 1968, from uni- + sex.

unison --- 1574, from M.Fr. unisson "unison, accord of sound" (16c.), from M.L. unisonus "having one sound, sounding the same," from L.L. unisonius "in immediate sequence in the scale, monotonous," from L. uni- "one" (see one) + sonus "sound" (see sound (n.1)). Sense of "harmonious agreement" is first attested 1650.

unit --- 1570, "single number regarded as an undivided whole," alteration of unity on the basis of digit. Popularized in John Dee's Eng. translation of Euclid, to express Gk. monas (Dee says unity formerly was used in this sense). Meaning "single thing regarded as a member of a group" is attested from 1642. Extended sense of "a quantity adopted as a standard of measure" is from 1738. Sense of "group of wards in a hospital" is attested from 1893.

Unitarian --- 1687, "one who rejects the doctrine of the Trinity," from Mod.L. unitarius (1656), from L. unitas (see unity).

unite --- 1432, from L. unitus, pp. of unire "to unite," from unus "one" (see one). United Kingdom is recorded from 1737. The phrase United States has been used since 1617, originally with ref. to Holland; the North American republic first so called in 1776. United Nations (1942) originally meant "the Allied nations at war with the Axis powers;" the international body (officially the United Nations Organization) was chartered in 1945. United Provinces were the seven northern provinces of the Netherlands, allied from 1579, later developing into the kingdom of Holland.

unity --- c.1300, from Anglo-Fr. unite, O.Fr. unite (c.1200), from L. unitatem (nom. unitas) "oneness, sameness, agreement," from unus "one" (see one).

universal --- c.1374, from O.Fr. universel (12c.), from L. universalis "of or belonging to all," from universus "all together, whole, entire" (see universe). In mechanics, a universal joint (1676) is one which allows free movement in any direction; in theology universalism (1805) is the doctrine of universal salvation (universalist in this sense is attested from 1626). Universal product code is recorded from 1974.

universe --- 1589, "the whole world, cosmos," from O.Fr. univers (12c.), from L. universum "the universe," noun use of neut. of adj. universus "all together," lit. "turned into one," from unus "one" (see one) + versus, pp. of vertere "to turn" (see versus). Properly a loan-translation of Gk. to holon "the universe," noun use of neut. of adj. holos "whole" (see safe (adj.)).

university --- c.1300, "institution of higher learning," also "body of persons constituting a university," from Anglo-Fr. université, O.Fr. universitei (13c.), from M.L. universitatem (nom. universitas), in L.L. "corporation, society," from L., "the whole, aggregate," from universus "whole, entire" (see universe). In the academic sense, a shortening of universitas magistrorum et scholarium "community of masters and scholars;" superseded studium as the word for this.

unjust --- 1382, of persons, from un- (1) "not" + just. Of actions, attested from c.1400.

unjustified --- c.1340, "not punished or executed," from un- (1) "not" + pp. of justify. Meaning "not proven to be right or proper" is attested from 1685.

unkempt --- 1579, from un- (1) "not" + kempt "well-combed, neat," from variant pp. of O.E. cemban "to comb," from P.Gmc. *kambijan, from *kamb- "comb" (see comb). Form unkembed iss recorded from 1390. The verb kemb is rare after 1400s, but its negative pp. form endures.

unkind --- c.1225 (implied in unkindly), "strange, foreign, unnatural," from un- (1) "not" + kind. Meaning "lacking in kindness" is recorded from 1362.

unknown (adj.) --- c.1300, "strange, unfamiliar" (of persons, places), from un- (1) "not" + pp. of know. Cf. O.E. ungecnawen. In ref. to facts, attested from c.1330. The noun meaning "unknown person" is recorded from 1597.

unlace --- c.1300, from un- (2) + lace (v.).

unlamented --- 1595, from un- (1) "not" + pp. of lament.

unlawful --- c.1300, from un- (1) "not" + lawful (see law). Unlawful assembly is recorded in statutes from 1485.

unleaded --- 1611, from un- (1) "not" + leaded (see lead (n.)). In ref. to gasoline, from 1965.

unleash --- 1671, from un- (2) + verbal derivative of leash (n.).

unless --- 1467, earlier onlesse (c.1440), from on lesse (than) "on a less condition (than)," the first syllable originally on, but the negative connotation and the lack of stress changed it to un-.

unlettered --- c.1340, "not possessed of book-learning," from un- (1) "not" + lettered (see letter (n.)). An Anglicized form of illiterate. Cf. M.Du. ongelettert.

unlicensed --- 1634, from un- (1) "not" + licensed (see licence).

unlike --- c.1200, "Not resembling," from un- (1) "not" + like. Cf. O.E. ungelic, O.Fris. unlik, O.N. ulikr, M.Da. ulige. Unlikely "not likely to occur" is attested from 1375 (cf. O.N. ulikligr, M.Da. uligelig). Meaning "not likely to be true" is recorded from 1592.

unlimber --- 1802, "to free (a gun) from its limber," usually for the purpose of bringing it into action, from un- (2) + limber (n.). Fig. sense is attested from 1864.

unlimited --- c.1445, from un- (1) "not" + pp. of limit (v.).

unlisted --- 1644, from un- (1) "not" + pp. of list (v.). In ref. to stocks, attested from 1905; of phone numbers, from 1937 (Amer.Eng.).

unlivable --- 1869, from un- (1) "not" + livable (see live (v.)).

unload --- 1523, in ref. to cargo, from un- (2) + load (v.). Fig. sense (in ref. to feelings, etc.) is recorded from 1593.

unlock --- c.1400, from un- (2) + lock (v.). Fig. sense is attested from 1531.

unlooked --- c.1300, "not attended to, neglected," from un- (1) "not" + pp. of look. With for, "unexpected," attested from 1535.

unloose --- 1393, "to set free," from un- (2), used here emphatically, + loose.

unloved --- 1395, from un- (1) "not" + pp. of love (v.).

unlovely --- 1377, "not evoking feelings of love," from un- (1) "not" + lovely. Meaning "ugly" is recorded from 1393.

unlucky --- 1530, "marked by misfortune or failure," from un- (1) "not" + lucky (see luck). Cf. W.Fris. unlokkich, M.L.G. unluckich. Sense of "boding ill" is recorded from 1547; that of "having bad luck" is from 1552; that of "bringing bad luck" is from 1586.

unmade --- c.1250, "not yet made," from un- (1) "not" + pp. of make. Unmake "to reduce to an unmade condition" is recorded from 1426 (cf. M.Du. ontmaken, Ger. entmachen); fig. sense of "to ruin" is recorded from 1605.

unman --- 1598, "to deprive of the attributes of a human being," from un- (2) + verbal derivative of man (n.). Meaning "to deprive of manly courage" is attested from c.1600; that of "to emasculate" is from 1684. Unmanly "degrading to a human" is attested from c.1475 (cf. M.Du. onmamlijc, Ger. unmännlich). Unmanned "not furnished with a crew" is from 1544.

unmarked --- c.1400, "having been given no mark," from un- (1) "not" + pp. of mark (v.). Cf. O.N. umarkaðr. Meaning "not noticed or observed" is recorded from 1533.

unmarried --- 1297, from un- (1) "not" + pp. of marry.

unmask --- 1586 in fig. sense, 1602 in lit. sense, from un- (2) + mask (v.).

unmatched --- 1581, "unrivaled," from un- (1) "not" + pp. of match (v.).

unmeet --- O.E. unmæte "immoderate, excessive," from un- (1) "not" + meet (adj.). Cf. O.H.G. unmazi. Meaning "unfitting" is from 1529; that of "unsuited" (for some purpose) is from c.1522.

unmentionable (adj.) --- 1837, from un- (1) "not" + mentionable (see mention (v.)). Unmentionables "trousers" is attested from 1823; meaning "underwear" is recorded from 1910.

unmitigated --- 1599, from un- (1) "not" + pp. of mitigate.

unmolested --- 1531, from un- (1) "not" + pp. of molest.

unmoor --- 1497, "to free from moorings," from un- (2) + moor (v.).

unmoved --- c.1375, "not affected by emotion or excitement," from un- (1) "not" + pp. of move (v.).

unnamed --- 1509, "not mentioned by name." from un- (1) "not" + pp. of name (v.). Cf. O.Fris. unnamed, M.Du. ongenaemt.

unnatural --- c.1425, "not in accord with physical nature," from un- (1) "not" + natural. Meaning "artificial" is attested from 1746; that of "at variance with moral standards" is from 1529.

unnecessary --- 1548, from un- (1) "not" + necessary.

unnerve --- 1621, "to destroy the strength of," from un- (2) + nerve. Meaning "to deprive of courage" is recorded from 1704.

unobserved --- 1612, from un- (1) "not" + pp. of observe.

unobstructed --- 1659, from un- (1) "not" + pp. of obstruct.

unoccupied --- c.1380, "idle," from un- (1) "not" + pp. of occupy. In ref. to ground, etc., attested from c.1425.

unofficial --- 1798, from un- (1) "not" + official.

unopposed --- 1659, from un- (1) "not" + pp. of oppose.

unoriginal --- 1667, "having no origin, uncreated," from un- (1) "not" + original (adj.). Meaning "derivative, second-hand" is recorded from 1774.

unorthodox --- 1657, from un- (1) "not" + orthodox.

unpack --- 1472, from un- (2) + pack. Cf. Du. ontpakken.

unpaid --- 1375, in ref. to persons, from un- (1) "not" + pp. of pay. Of debts, attested from 1483.

unpalatable --- 1682, from un- (1) "not" + palatable (see palate).

unparalleled --- 1594, from un- (1) "not" + pp. of parallel.

unpaved --- 1533, from un- (1) "not" + pp. of pave.

unperturbed --- 1420, from un- (1) "not" + pp. of perturb.

unpleasant --- 1538, from un- (1) "not" + pleasant.

unpolished --- 1382, from un- (1) "not" + pp. of polish (v.). In ref. to style, language, etc., attested from c.1489.

unpopular --- 1647, from un- (1) "not" + popular.

unpracticed --- 1551, from un- (1) "not" + pp. of practice (v.).

unprecedented --- 1623, from un- (1) "not" + precedented (see precedent (n.)). In common use from c.1760.

unpredictable --- 1857, from un- (1) "not" + predictable (see predict).

unprejudiced --- 1613, from un- (1) "not" + pp. of prejudice.

unprepared --- 1549, from un- (1) "not" + pp. of prepare (see preparation).

unpretentious --- 1859, from un- (1) "not" + pretentious.

unprincipled --- 1634, "not instructed" (in something), from un- (1) "not" + principled (see principle). Meaning "not honorable" is recorded from 1644.

unproductive --- 1756, from un- (1) "not" + productive.

unprofessional --- 1806, from un- (1) "not" + professional (see profession).

unprofitable --- c.1325, from un- (1) "not" + profitable (see profit (n.)).

unpromising --- 1663, from un- (1) "not" + promising (see promise).

unprovoked --- 1585, from un- (1) "not" + pp. of provoke.

unpublished --- 1607, from un- (1) "not" + pp. of publish. In ref. to an author, attested from 1934.

unqualified --- 1556, "not having necessary qualifications, from un- (1) "not" + pp. of qualify. Meaning "not modified or limited" is recorded from 1796.

unquestionable --- 1603, from un- (1) "not" + questionable (see question).

unquote --- 1935, from un- (2) + quote (v.). Originally (obviously) in speaking, first written record is in a letter of e.e. cummings.

unravel --- 1603, from un- (2) + ravel.

unready --- c.1340, "not prepared," from un- (1) "not" + ready. In Eng. history, applied to Anglo-Saxon King Ethelred II (d.1016), where it preserves the fuller original sense of O.E. ungeræd "ill-advised, rede-less, no-counsel" and plays on the king's name (which lit. means "good-counsel"). The epithet is attested from c.1210.

unreal --- 1605, "not real," from un- (1) "not" + real (adj.). Slang sense of "wonderful, great" is first recorded 1965.

unreasonable --- c.1340, from un- (1) "not" + reasonable.

unreconstructed --- 1867, "not reconciled to the outcome of the American Civil War," from un- (1) "not" + pp. of reconstruct.

unrefined --- 1595, "not refined in manners," from un- (1) "not" + pp. of refine. Meaning "not free from gross matter" is recorded from c.1610.

unreformed --- 1528, from un- (1) "not" + pp. of reform.

unregenerate --- 1612, from un- (1) "not" + regenerate (see regeneration).

unrelated --- 1661, "not akin," from un- (1) "not" + pp. of relate. Meaning "Not in any relationship" is attested from 1668; that of "not told" is from 1764.

unrelenting --- 1588, from un- (1) "not" + relenting (see relent).

unreliable --- 1840, from un- (1) "not" + reliable. First recorded in De Quincey, who said it was coined by Coleridge.

unrepentant --- c.1380, from un- (1) "not" + repentant (see repent).

unrequited --- 1542, from un- (1) "not" + pp. of requite.

unresolved --- 1577, "undecided" (of questions), from un- (1) "not" + pp. of resolve (v.). Meaning "uncertain in opinion" is attested from 1597.

unrest --- c.1340, from un- (2) + rest. Cf. W.Fris. onrest, M.L.G. unreste, Ger. unrast, M.Du. onruste.

unrestrained --- 1586, from un- (1) "not" + pp. of restrain.

unripe --- O.E. unripe "premature" (in ref. to death), from un- (1) "not" + ripe. Meaning "immature, not fully developed (of fruit, etc.) is recorded from c.1250. Cf. M.Du. onrijp, O.H.G. unrifi, Ger. unreif.

unroll --- 1412, from un- (2) + roll (v.).

unruffled --- 1659, in fig. sense, from un- (1) "not" + pp. of ruffle. Lit. meaning, in ref. to feathers, leaves, etc., is recorded from 1816.

unruly --- 1400, from un- (1) "not" + obsolete ruly "amenable to rule," from rule.

unsafe --- 1597, "involving risk or danger," from un- (1) "not" + safe (adj.).

unsaid --- O.E. unsæd, from un- (1) "not" + pp. of say. Cf. M.Du. ongeseit, Ger. ungesagt, O.N. usagðr.

unsalted --- c.1440, from un- (1) "not" + pp. of salt (v.). Cf. N.Fris. unsalted, Swed. osaltad, Dan. usaltet.

unsatisfied --- c.1430, from un- (1) "not" + pp. of satisfy. Unsatisfactory is attested from 1637.

unsaturated --- 1758, from un- (1) "not" + pp. of saturate.

unsavory --- c.1225, "tasteless, insipid," from un- (1) "not" + savory (adj.). Meaning "unpleasant or disagreeable to the taste" is attested from c.1380; of persons, from 1401.

unscathed --- c.1375, from un- (1) "not" + pp. of scathe. Mainly in Scottish before 19c. Cf. O.N. ostaðaðr, Swed. oskadad.

unschooled --- 1589, "untrained," from un- (1) "not" + pp. of school (v.).

unscramble --- restore to order, 1923, from un- (2) + scramble (v.). The original notion probably is from the old retort about the impossibility of unscrambling eggs.

unscrupulous --- 1803, from un- (1) "not" + scrupulous (see scruple).

unseal --- c.1425, from un- (2) + seal (v.). Cf. M.Du. ontsegelen, O.H.G. intsigilan. Unsealed is recorded from 1377.

unseasonable --- c.1448, "inopportune," from un- (1) "not" + seasonable (see season (n.)). In ref. to weather, "not appropriate to the time of year," it is recorded from 1513.

unseasoned --- 1582, "not made palatable by seasoning," from un- (1) "not" + pp. of season (v.). Meaning "not habituated by experience" is recorded from 1601.

unseat --- 1596, "to throw down from a seat" (especially on horseback), from un- (2) + seat (v.). Meaning "to deprive of rank or office" is attested from 1611; especially of elected office in a representative body from 1834.

unseemly --- 1310, "unfitting, indecent," from un- (1) "not" + seemly. Cf. O.N. usoemiligr.

unseen --- c.1225, from un- (1) "not" + pp. of see (v.). Cf. O.E. ungesewen, M.Du. ongesien, Du. ongezien, O.H.G. ungesëhan, Ger. ungesehen, O.N. usenn.

unselfish --- 1698, from un- (1) "not" + selfish. Cf. Dan. uselvisk, Swed. osjälfvisk.

unsettle --- 1598, "undo from a fixed position, from un- (2) + settle. Of the mind, feelings, etc., attested from 1644. Unsettled "not peaceful, not firmly established" is recorded from 1591. Meaning "not occupied by settlers" is attested from 1724.

unshaken --- c.1460, "not agitated," from un- (1) "not" + pp. of shake. Meaning "not moved from a firm position" is recorded from 1548.

unsightly --- c.1425, "displeasing to the eye," from un- (1) "not" + sightly (see sight). Cf. M.Du. onsichtlijc "invisible, ugly," M.H.G. unsihtlih "invisible."

unsinkable --- 1655, from un- (1) "not" + sinkable (see sink (v.)).

unskilled --- 1581, from un- (1) "not" + skilled (see skill).

unsmiling --- 1826, from un- (1) "not" + smiling (see smile (v.)).

unsociable --- 1600, from un- (1) "not" + sociable.

unsolicited --- 1588, from un- (1) "not" + pp. of solicit.

unsophisticated --- 1630, "unmixed," from un- (1) "not" + sophisticated (see sophistication). Meaning "ingenuous, natural, inexperienced" is recorded from 1665.

unsought --- c.1225, from un- (1) "not" + pp. of seek. Cf. M.Du. ongesocht, Du. ongezocht, M.H.G. ungesuochet, Ger. ungesucht.

unsound --- c.1320, of persons, "diseased, wounded," from un- (1) "not" + sound (adj.). Cf. M.L.G. unsund, M.Du. ongesont, Ger. ungesund. Meaning "morally corrupt" is recorded from c.1300; that of "not mentally healthy" is from 1547. Sense of "not based on reasoning or fact" is attested from 1595.

unsparing --- showing no mercy, 1586, from un- (1) "not" + sparing (see spare (v.)).

unspeakable --- c.1400, "inexpressible," from un- (1) "not" + speakable (see speak). Meaning "indescribably bad or wicked" is recorded from 1831.

unspoiled --- c.1500, "not plundered," from un- (1) "not" + pp. of spoil (v.). Meaning "not deteriorated" is attested from 1732.

unspoken --- 1375, from un- (1) "not" + pp. of speak. Cf. M.Du. ongesproken, M.L.G. ungesproken.

unsportsmanlike --- 1754, from un- (1) "not" + sportsmanlike (see sport (n.)). Unsporting is attested from 1859.

unstable --- c.1225, "apt to move," from un- (1) "not" + stable (adj.). Cf. M.H.G. unstabel. Meaning "liable to fall" is recorded from c.1300; sense of "fickle" is attested from c.1290.

unsteady --- 1598, from un- (1) "not" + steady (adj.). Cf. O.Fris. unstadich, Ger. unstätig, M.Du. onstadich.

unstinted --- 1480, from un- (1) "not" + pp. of stint (v.).

unstrung --- 1598, "with strings relaxed" (of a harp, etc.), from un- (1) "not" + pp. of string (v.). Transf. sense of "weakened, unnerved" is recorded from 1692.

unsuccessful --- 1617, from un- (1) "not" + successful (see success).

unsung --- 1422, "not uttered in a song," from un- (1) "not" + pp. of sing. Cf. Ger. ungesungen. Meaning "not celebrated" is recorded from 1667.

unsupervised --- 1899, from un- (1) "not" + pp. of supervise.

unsure --- c.1400, "not safe against attack," also "lacking certainty," from un- (1) "not" + sure.

unsuspected --- 1530, from un- (1) "not" + pp. of suspect (v.).

untainted --- 1590, in the moral sense; c.1600 in the physical sense; from un- (1) "not" + pp. of taint (v.).

untamed --- c.1340, from un- (1) "not" + pp. of tame. Cf. O.N. utamdr, O.H.G. ungizamot.

untangle --- 1550, from un- (2) + tangle.

untempered --- 1577, from un- (1) "not" + pp. of temper. Cf. M.Du. ongetempert, M.H.G. ungetempert.

untenable --- 1647, "incapable of being held against attack," from un- (1) "not" + pp. of tenable. Fig. sense is recorded from 1692.

unthinkable --- 1430, "too large to be conceived, unimaginable," from un- (1) "not" + thinkable (see think). Meaning "incapable of being framed by thought" is recorded from c.1445. Unthinking "unreflecting" is attested from 1676.

untidy --- c.1225. "untimely, unseasonable, unsuitable," from un- (1) "not" + tidy. Cf. W.Fris. ontidich, M.Du. ontidich, Du. ontijdig, O.H.G. unzitich, Ger. unzeitig, Norw. utidig "untimely, unseasonable, unfavorable." Meaning "poorly cared for, not neat" is recorded from c.1350.

untie --- O.E. untiegan, from un- (2) + tie (v.).

until --- c.1200, from O.N. und "as far as, up to" (related to O.E. end; see end) + till "until, up to" (see till). Originally also used of persons and places. Cf. Swed. intill, Dan. indtil. The Mod.Ger. equivalent, bis (O.H.G. biaz), is a similar compound, of O.H.G. bi "by, at, to" and zu "to."

untimely --- 1535, "coming before the proper or usual time," from un- (1) "not" + timely. Cf. M.Dan. utimelig, of weather, etc.

unto --- c.1250, 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 O.E. *und- "up to," cognate of the first element in until. Since 18c., chiefly in dignified, archaic, or Biblical styles.