Online Etymology Dictionary

jaunt (n.): 1670s in modern sense of "short pleasure trip," earlier "tiresome journey" (1590s), earlier as a verb, "tire a horse by riding back and forth on it" (1560s), of unknown origin, perhaps from some obscure Old French word. As a verb in the modern sense from 1640s. Related: Jaunted; jaunting.
jaunty (adj.): 1660s, "elegant, stylish," from French gentil "nice, pleasing," in Old French "noble" (see gentle). Form reflects attempt to render the French pronunciation of gentil. Meaning "easy and sprightly in manner" first attested 1670s. Related: Jauntily; jauntiness.
java (n.): 1850, originally a kind of coffee grown on Java and nearby islands of modern Indonesia. By early 20c., coffee generally. The island name is shortened from Sanskrit Yavadvipa "Island of Barley," from yava "barley" + dvipa "island."
javelin (n.): late 15c., from Middle French javeline (15c.), fem. diminutive of Old French javelot "a spear," probably from Gaulish (cf. Old Irish gabul "fork;" Welsh gafl "fork," gaflach "feathered spear"), ultimately from PIE *ghabholo- "a fork, branch of a tree." Also found in Italian (giavelotto) and Middle High German (gabilot). Javelot also was borrowed in Middle English, but this is the form of the word that has endured.
javelot (n.): see javelin.
jaw (n.): late 14c., "the bones of the mouth," perhaps from Old French joue "cheek," from Gaulish *gauta "cheek," or perhaps a variant of Germanic words related to chew (q.v.); cf. also jowl. Replaced Old English ceace, ceafl.
jaw (v.): 1610s, "to catch in the jaws, devour," from jaw (n.). In slang from 1748, "to gossip, to speak" 1810, "to scold." Related: Jawed; jawing. Hence 19c. U.S. slang jawsmith "talkative person" (1887).
jaw-breaker (n.): also jawbreaker 1839, "word hard to pronounce" (jawbreakingly, in reference to pronouncing words, is from 1824), from jaw (n.) + agent noun from break (v.). As a type of candy, by 1911.
jawbone (n.): mid-15c., from jaw (n.) + bone (n.). Hence jawboning "lecturing, hectoring," a term associated with the U.S. Lyndon Johnson presidential administration (1966); cf. jaw (v.).
jay (n.): c.1300, common European bird (Garrulus glandarinus), from Old North French gai, Old French jai "magpie, jay," from Late Latin gaius "a jay," probably echoic and supposedly influenced by Latin Gaius, a common Roman proper name. For other bird names from proper names, cf. martin and parrot. Applied to the North American blue jay (Cyanocitta cristata) from 1709. Applied to humans in sense of "impertinent chatterer, flashy dresser" from 1620s.
jay (adj.): "fourth-rate, worthless" (e.g. a jay town), 1888, American English, apparently from some disparaging sense of jay (n.). Perhaps from a decaying or ironical use of jay "flashy dresser."
jaybird (n.): 1660s, from jay + bird (n.). It appears after the time jay began to be used of persons, too.
Jaycee (n.): 1946, American English, from pronunciation of J.C., in Junior Chamber (of Commerce).
jayhawker (n.): American English, 1858, originally "freebooter, guerrilla, Kansas irregular" (especially one who came from the North). Hence back-formed verb jayhawk "harass" (1866).
jaywalking (n.): by 1912, American English (said in original citation to be a Kansas City term), from jay, perhaps with notion of boldness and impudence. Related: Jaywalk; jaywalker.
jazz (v.): "to speed or liven up," 1917, from jazz (n.). Related: jazzed; jazzing.
jazz (n.): by 1912, American English, first attested in baseball slang; as a type of music, attested from 1913. Probably ultimately from Creole patois jass "strenuous activity," especially "sexual intercourse" but also used of Congo dances, from jasm (1860) "energy, drive," of African origin (cf. Mandingo jasi, Temne yas), also the source of slang jism.
If the truth were known about the origin of the word 'Jazz' it would never be mentioned in polite society. ["Étude," Sept. 1924]
All that jazz "et cetera" first recorded 1939.
Jazz Age: 1921; see jazz (n.); popularized 1922 in writings of F. Scott Fitzgerald; usually regarded as the years between the end of World War I (1918) and the Stock Market crash of 1929.
We are living in a jazz age of super-accentuated rhythm in all things; in a rhythm that (to "jazz" a word) is super-normal, a rhythm which is the back-flare from the rhythm of a super war. ["Jacobs' Band Monthly," Jan. 1921]
jazzbo (n.): 1917, "low, vulgar jazz," from jazz. Later in 20c. in use as a derogatorty term for persons, especially blacks.
Jazzercise (n.): 1977, originally a proprietary name, from jazz (n.) + ending from exercise.
jazzetry (n.): "poetry reading accompanioed by jazz music," 1959, from jazz (n.) + poetry.
jazzy (adj.): 1919, from jazz (n.) + -y (2). Related: Jazzily; jazziness.
je ne sais quoi (n.): "an inexpressible something," French, literally "I do not know what."
[T]hey are troubled with the je-ne-scay-quoy, that faign themselves sick out of niceness but know not where their own grief lies, or what ayls them. [Thomas Blount, "Glossographia," 1656]
jealous (adj.): c.1200, gelus, later jelus (early 14c.), "possessive and suspicious," originally in the context of sexuality or romance; in general use late 14c.; also in a more positive sense, "fond, amorous, ardent," from c.1300, from Old French jalos "keen, zealous; avaricious; jealous" (12c., Modern French jaloux), from Late Latin zelosus, from zelus "zeal," from Greek zelos, sometimes "jealousy," but more often in a good sense ("emulation, rivalry, zeal"). See zeal. In biblical language (early 13c.) "tolerating no unfaithfulness."
Most of the words for 'envy' ... had from the outset a hostile force, based on 'look at' (with malice), 'not love,' etc. Conversely, most of those which became distinctive terms for 'jealousy' were originally used also in a good sense, 'zeal, emulation.' [Buck, pp.1138-9]
Among the ways to express this in other tongues are Swedish svartsjuka, literally "black-sick," from phrase bara svarta strumpor "wear black stockings," also "be jealous." Danish skinsyg "jealous," literally "skin-sick," is from skind "hide, skin" said to be explained by Swedish dialectal expression fa skinn "receive a refusal in courtship."
jealously (adv.): late 14c., "in a zealous manner;" 1718, "in a suspicious and possessive manner," from jealous + -ly (2).
jealousy (n.): c.1200, of God; c.1300, of persons, from Old French jalousie "enthusiasm, love, longing, jealousy" (12c.), from jalos (see jealous). Meaning "zeal, fervor, devotion" is late 14c.
Jean: masc. proper name, from French equivalent of John. Fem. proper name is from French equivalent of Jane.
jean (n.): "twilled cotton cloth," mid-15c., from Middle French jean fustian "fustian (a type of twilled cotton cloth) of Genoa," the city in Italy, from Old French Jannes "Genoa," from Latin Genua (see Genoa). The plural form jeans became standard 19c.
jeans (n.): see jean.
Jedi (n.): characters in the "Star Wars" sagas, 1977, apparently an invented word.
jeep (n.): early 1941, American English military slang, from G.P. "general purpose (car)," but influenced by Eugene the Jeep (who had extraordinary powers but only said "jeep"), from E.C. Segar's comic strip "Thimble Theater" (also home of Popeye the Sailor). Eugene the Jeep first appeared in the strip March 13, 1936. The vehicle was in development from 1940, and the Army planners' initial term for it was light reconnaissance and command car.
jeepers: 1900, American English, euphemistic alteration of Jesus.
jeer (v.): 1550s, gyr, "to deride, to mock," of uncertain origin; perhaps from Dutch gieren "to cry or roar," or German scheren "to plague, vex," literally "to shear." OED finds the suggestion that it is an ironical use of cheer "plausible and phonetically feasible, ... but ... beyond existing evidence." Related: Jeered; jeering.
jeer (n.): 1620s, from jeer (v.).
Jeeves: personification of the perfect valet, 1930, from character in P.G. Wodehouse's novels.
Jeez: also jeeze, 1922, American English, euphemistic corruption Jesus.
Jeff: shortened or familiar form of masc. proper name Jeffrey; in early to mid-20c., sometimes used by U.S. blacks to indicate a Southern white hick, probably from Jeff Davis, president of the Confederate States of America.
Jeffersonian: 1799 (n.), 1800 (adj.), in reference to the politics and policies of U.S. revolutionary and president Thomas Jefferson.
Jeffrey: masc. proper name, from Old French Jeufroi, Jefroi, variants of Geuffroi (see Geoffrey).
Jehosaphat: biblical name (II Sam. viii:16), used as a mild expletive in American English from 1857.
Jehovah: 1530, Tyndale's erroneous transliteration of Hebrew Tetragramaton YHWH using vowel points of Adhonai "my lord" (see Yahweh). Used for YHWH (the full name being too sacred for utterance) in four places in the Old Testament in the KJV where the usual translation lord would have been inconvenient; taken as the principal and personal name of God.

The vowel substitution was originally made by the Masoretes as a direction to substitute Adhonai for "the ineffable name." European students of Hebrew took this literally, which yielded Latin JeHoVa (first attested in writings of Galatinus, confessor to Leo X, 1516). Jehovah's Witnesses "member of Watchtower Bible and Tract Society" first attested 1933; the organization founded c.1879 by Charles Taze Russell (1852-1916); the name from Isa. xliii:10.
Jehovist (n.): the presumed authnor or authors of the parts of the Hexateuch in which the divine name is written Yhwh (see Jehovah) + -ist. Opposed to the Elohist.
Jehu: "fast, skillful driver," 1680s, from Jehu, a king of Israel in the Old Testament, who "driveth furiously" (II Kings ix:20).
jejune (adj.): 1610s, "dull in the mind, flat, insipid," from Latin ieiunus "empty, dry, barren," literally "fasting, hungry," of obscure origin.
jejunum (n.): late 14c., from Latin ieiunum, neuter of ieiunus (see jejune). Translating Greek nestis (Galen). So called because it typically is found empty during dissections, perhaps because it would tend to drain in a body laid on its back.
Jekyll and Hyde: in reference to opposite aspects of a person's character, from Robert Louis Stevenson's story, "The Strange Case of Dr. Jekyll and Mr. Hyde," published 1886. The surname Jekyll is of Breton origin and was originally a personal name.
"Though so profound a double-dealer, I was in no sense a hypocrite. Both sides of me were in dead earnest; I was no more myself when I laid aside restraint and plunged in shame, than when I labored, in the eye of day, at the furtherance of knowledge or the relief of sorrow and suffering." [Robert Louis Stevenson, "The Strange Case of Dr. Jekyll and Mr. Hyde," 1886]
jell (v.): 1830, American English, probably a back-formation of jelly (v.). Related: Jelled; jelling. Figurative sense is first attested 1908. Middle English had gelen "congeal," but it disappeared 15c.
jellied (adj.): 1590s, past participle adjective from jelly (v.).
Jello (n.): from Jell-O, trademark for powdered gelatin food, registered 1934 by The Jell-o Company of Canada, Ltd., Montreal, Quebec, Canada.
jelly (n.): late 14c., from Old French gelee "a frost; jelly," noun use of fem. past participle of geler "congeal," from Latin gelare "to freeze," from gelu "frost" (see cold (adj.)).