Online Etymology Dictionary

vanguard (n.): mid-15c., vaunt garde, from Middle French avant-garde, from avant "in front" (see avant) + garde "guard" (see guard (n.)). Communist revolutionary sense is recorded from 1928.
vanilla (n.): 1660s, "pod of the vanilla plant," from Spanish vainilla "vanilla plant," literally "little pod," diminutive of vaina "sheath," from Latin vagina "sheath of an ear of grain, hull of a plant" (see vagina). So called from the shape of the pods. European discovery 1521 by Hernando Cortes' soldiers on reconnaissance in southeastern Mexico. Meaning "flavoring extracted from the vanilla bean" is attested by 1728. Meaning "conventional, of ordinary sexual preferences" is 1970s, from notion of whiteness and the common choice of vanilla ice cream.
vanillin (n.): substance prepared from fruit of the vanilla plant, 1859, from vanilla + -in (2).
vaniloquence (n.): "idle talk," 1620s, from Latin vaniloquentia, from vanus "idle, empty" (see vain) + loquens, from loqui "to speak" (see locution).
vanish (v.): "disappear quickly," c. 1300, from shortened form of esvaniss-, stem of Old French esvanir "disappear; cause to disappear," from Vulgar Latin *exvanire, from Latin evanescere "disappear, pass away, die out," from ex- "out" (see ex-) + vanescere "vanish," inchoative verb from vanus "empty" (see vain). Related: Vanished; vanishing; vanishingly. Vanishing point in perspective drawing is recorded from 1797.
vanity (n.): c. 1200, "that which is vain, futile, or worthless," from Old French vanite "self-conceit; futility; lack of resolve" (12c.), from Latin vanitatem (nominative vanitas) "emptiness, aimlessness; falsity," figuratively "vainglory, foolish pride," from vanus "empty, vain, idle" (see vain). Meaning "self-conceited" in English is attested from mid-14c. Vanity table is attested from 1936. Vanity Fair is from "Pilgrim's Progress" (1678).
vanquish (v.): mid-14c., "to defeat in battle, conquer," from Old French venquis-, extended stem of veintre "to defeat," from Latin vincere "defeat" (see victor). Influenced in Middle English by Middle French vainquiss-, present stem of vainquir "conquer," from Old French vainkir, alteration of veintre. Related: Vanquished; vanquishing.
vantage (n.): early 14c., "advantage, profit," from Anglo-French vantage, from Old French avantage "advantage, profit, superiority" (see advantage). Vantage point "favorable position" attested from 1865; a similar notion was in earlier vantage ground (1610s).
vapid (adj.): 1650s, "flat, insipid" (of drinks), from Latin vapidus "flat, insipid," literally "that has exhaled its vapor," related to vappa "stale wine," and probably to vapor "vapor." Applied from 1758 to talk and writing deemed dull and lifeless. Related: Vapidly; vapidness.
vapidity (n.): 1721, from vapid + -ity.
vapor (n.): late 14c., from Anglo-French vapour, Old French vapor "moisture, vapor" (13c., Modern French vapeur) and directly from Latin vaporem (nominative vapor) "a warm exhalation, steam, heat," of unknown origin. Vapors "fit of fainting, hysteria, etc." is 1660s, from medieval notion of "exhalations" from the stomach or other organs affecting the brain.
vaporetto (n.): Venetian public transit canal-motorboat, 1926, from Italian vaporetto, diminutive of vapore "steam," from Latin vapor (see vapor (n.)).
vaporization (n.): also vaporisation, 1788, noun of action from vaporize. In same sense Middle English had vaporacioun (late 14c.).
vaporize (v.): 1630s, "to smoke" (tobacco), from vapor + -ize. Later "convert into vapor, cause to become vapor" (1803), and "spray with fine mist" (1900). Intransitive sense "become vaporous" is from 1828. Related: Vaporized; vaporizing. An earlier verb was simply vapor (c. 1400, transitive and intransitive), from Latin vaporare.
vaporizer (n.): 1846, agent noun from vaporize.
vaporous (adj.): late 14c., from Late Latin vaporosus "full of steam," from Latin vaporus, from vapor (see vapor).
vapour (n.): chiefly British English spelling of vapor; see -or.
vappa (n.): "wine that has lost its flavor," c. 1600, from Latin vappa "wine without flavor," figuratively "a good-for-nothing" (see vapid).
vaquero (n.): 1826, from Spanish, literally "cowboy," from vaca "cow," from Latin vacca (see vaccination).
Varangian (n.): one of the Northmen who ravaged the Baltic coast in 9c. and by tradition overran part of western Russia and founded a dynasty there," 1788, from Medieval Latin Varangus, from Byzantine Greek Barangos, a name ultimately (via Slavic) from Old Norse væringi "a Scandinavian," properly "a confederate," from var- "pledge, faith," related to Old English wær "agreement, treaty, promise," Old High German wara "faithfulness" (see very). Attested in Old Russian as variagi; surviving in Russian varyag "a pedlar," Ukrainian varjah "a big strong man."
variability (n.): 1771, from variable (Latin variabilis) + -ity.
variable (adj.): late 14c., of persons, "apt to change, fickle," from Old French variable "various, changeable, fickle," from Late Latin variabilis "changeable," from variare "to change" (see vary). Of weather, seasons, etc., attested from late 15c.; of stars, from 1788.
variable (n.): "quantity that can vary in value," 1816, from variable (adj.) in mathematical sense of "quantitatively indeterminate" (1710). Related: Variably; variability.
variance (n.): late 14c., "fact of undergoing change," from Old French variance "change, alteration; doubt, hesitation" and directly from Latin variantia, from stem of variare "to change" (see vary). Meaning "state of disagreement" is recorded from early 15c. The U.S. zoning sense of "official dispensation from a building regulation" is recorded from 1925.
variant (adj.): late 14c., "tending to change," from Old French variant and directly from Latin variantem (nominative varians), present participle of variare "to change" (see vary).
variant (n.): :something substantially the same, but in different form," 1848, from variant (adj.).
variate (n.): in statistics, 1899, from adjective variate (mid-15c.), from Latin variatus, past participle of variare (see vary).
variation (n.): late 14c., "difference, divergence," from Old French variacion "variety, diversity" and directly from Latin variationem (nominative variatio) "a difference, variation, change," from past participle stem of variare "to change" (see vary). The musical sense is attested from 1801. Related: Variational.
varicella (n.): "chicken-pox," medical Latin, 1764, irregular diminutive of variola (see variola). Related: Varicellous.
varices (n.): plural of varix "dilated vein" (c. 1400), from PIE root *wer- (1) "high raised spot or other bodily infirmity" (see vary (v.)).
varicocele (n.): "tumor in the scrotum," 1736, medical Latin, from Latin varic-, comb. form of varix "dilated vein" (see varices) + Latinized form of Greek kele "tumor."
varicolored (adj.): "diversified in color, motley," also vari-colored, 1660s, from Latin varius (see vary) + English colored (adj.).
varicose (adj.): early 15c., from Latin varicosus "with dilated veins," from varix (genitive varicis) "dilated vein," probably related to varus "bent outward, bow-legged" (see varus).
varied (adj.): "changed," early 15c., past participle adjective from vary (v.). From 1580s as "differing from one another;" as "characterized by variety," from 1732.
variegate (v.): 1650s "give variety to," from Late Latin variegatus "made of various sorts or colors," past participle of variegare "diversify with different colors," from varius "spotted, changing, varying" (see vary) + root of agere "to drive" (see act (n.)). Meaning "mark with different colors" is from 1660s (implied in Variegated). Related: vareiegating.
varietal (adj.): "having the characteristics of a variety," 1849, a biologists' word, from variety + -al (1). In reference to wines, "made from a single variety of grape," first attested 1941, American English. As a noun, in this sense, attested from 1955. Related: Varietally.
variety (n.): 1530s, "change of fortunes," from Middle French variété and directly from Latin varietatem (nominative varietas) "difference, diversity; a kind, variety, species, sort," from varius "various" (see vary). Meaning diversity, absence of monotony" is from 1540s; that of "collection of different things" is from 1550s; sense of "something different from others" is from 1610s. In reference to music hall or theatrical performances of a mixed nature, first recorded 1868, American English.
variform (adj.): 1660s, from Latin varius (see vary) + forma "form, shape" (see form (n.)).
varify (v.): "to make varied," c. 1600, from Latin vari-, stem of varius "different, diverse" (see vary) + -fy. Related: Varified; varifying.
variola (n.): "smallpox," 1771, medical Latin diminutive of Latin varius "changing, various," in this case "speckled, spotted" (see vary).
variorum (adj.): "an edition (especially of the complete works of a classical author) with notes of various commentators or editors," 1728, genitive masculine plural of Latin varius "different, diverse" (see vary), in phrase editio cum notis variorum. Its use with reference to an edition of an author's works containing variant readings (1955) is "deplored by some scholars" [OED].
various (adj.): early 15c., "characterized by variety," from Middle French varieux and directly from Latin varius "changing, different, diverse" (see vary). Meaning "different from one another, having a diversity of features" is recorded from 1630s. Related: Variously.
varlet (n.): mid-15c., "servant, attendant of a knight," from Middle French varlet (14c.), variant of vaslet, originally "squire, young man," from Old French vassal (see vassal). The meaning "rascal, rogue" is 1540s.
varmint (n.): 1530s, varment; the chiefly American English dialectal form varmint is attested from 1829; variant of vermin. Meaning "objectionable or troublesome person" is recorded from 1773.
varnish (n.): mid-14c., from Old French vernis "varnish" (12c.), from Medieval Latin vernix "odorous resin," of uncertain origin, perhaps from Late Greek verenike, from Greek Berenike, name of an ancient city in Libya (modern Bengasi) credited with the first use of varnishes. The town is named for Berenike II, queen of Egypt (see Berenice). Figurative sense of "specious gloss, pretense," is recorded from 1560s.
varnish (v.): late 14c.; see varnish (n.). Related: Varnished; varnishing. Century Dictionary defines varnishing day as "A day before the opening of a picture exhibition on which exhibitors have the privilege of retouching or varnishing their pictures after they have been placed on the walls." The custom is said to date to the early years of 19c.
varsity (adj.): 1825, "university," variant of earlier versity (1670s), shortened form of university. Compare varsal (1690s), short for universal; varmint from vermin; and Grose's "Dictionary of the Vulgar Tongue" (1788) has vardy as slang for verdict. "Used in English universities, and affected to some extent in American colleges" [Century Dictionary].
varus (n.): foot deformity in which the feet are extroverted, so that the inner ankle rests on the ground, while the sole of the foot is more or less turned outwards, 1800, from Latin varus "bent, bent outwards, turned awry, crooked," specifically "with legs bent inward, knock-kneed," of uncertain origin.
If the original meaning was 'with the legs opened', varus might be compared with vanus and vastus, and reflect *wa-ro- 'going apart, letting go'. In any case, none of the other etymologies proposed seems plausible. [de Vaan]
The use of classical varus and valgus, which denoted deformities of the legs, in modern medicine to describe deformities of the feet, was criticized by learned writers (see "Edinburgh Medical and Surgical Journal," July 1838).
varve (n.): "annual deposit of silt in a lake bed," 1912, from Swedish varv "turn, layer," related to Old Norse hverfa, Old English hwerfan "to turn round" (see wharf).
varvel (n.): "metal ring attached to the end of a hawk's jess and connecting it to the leash," 1530s, from Old French vervelle "falcon's leg fetter" (14c.), from Vulgar Latin derivation of Latin vertibulum "joint." Related: Varvels.