lubricous (adj.)
1530s, "lascivious," from Latin lubricus "slippery, smooth," from lubricus "slippery" (see lubricant (adj.)). Literal meaning "slippery, oily" is from 1650s in English; figurative sense of "shifty, elusive" is from 1640s. Also lubricious (1580s).
lubritorium (n.)
"place where automobiles are greased," 1928; from lubrication + ending from auditorium. Mentioned as an overworked suffix in the late 1920s; Mencken also lists infantorium, shavatorium, restatorium, hatatorium, and odditorium ("a slide-show").
lucency (n.)
1650s, from lucent + -cy. Lucence is from late 15c.
lucent (adj.)
mid-15c., "shining, bright, luminous," from Latin lucentem (nominative lucens), present participle of lucere "to shine" (see light (n.)). Meaning "lucid, clear" is from 1820. Related: Lucently.
Lucia
fem. proper name; see Lucy.
Lucian
masc. proper name, from Latin Lucianus (source also of French Lucien), a derivative of Roman Lucius, from lux (genitive lucis) "light" (see light (n.)). The Hellenistic Greek writer (his name Latinized from Greek Loukianos) was noted as the type of a scoffing wit.
lucid (adj.)
1590s, "bright, shining," from Latin lucidus "light, bright, clear," figuratively "perspicuous, lucid, clear," from lucere "to shine," from lux (genitive lucis) "light," from PIE root *leuk- "to shine, be bright" (see light (n.)). Sense of "easy to understand" first recorded 1786. Lucid interval "period of calm or temporary sanity" (1580s) is from Medieval Latin lucida intervalla (plural), which was common in medieval English legal documents (non est compos mentis, sed gaudet lucidis intervallis). Related: Lucidly; lucidness (1640s).
lucidity (n.)
1650s, "brightness," from French lucidité, from Late Latin luciditas, from lucidus (see lucid). Meaning "intellectual clarity" attested by 1851.
Lucifer
Old English Lucifer "Satan," also "morning star," from Latin Lucifer "morning star," literally "light-bringing," from lux (genitive lucis) "light" (see light (n.)) + ferre "carry" (see infer).

Belief that it was the proper name of Satan began with its use in Bible to translate Greek Phosphoros, which translates Hebrew Helel ben Shahar in Isaiah xiv:12 -- "How art thou fallen from heaven, O Lucifer, son of the morning!" [KJV] Because of the mention of a fall from Heaven, the verse was interpreted by Christians as a reference to Satan, even though it is literally a reference to the King of Babylon (see Isaiah xiv:4).

Lucifer match "friction match" is from 1831. Adjectival forms include Luciferian, Luciferine, Luciferous. There was a noted Bishop Lucifer of Cagliari in Sardinia in the 4th century, regarded locally as a saint.
luciferase (n.)
supposed enzyme found in fireflies and other glowing creatures, 1888, from French luciférase; see Lucifer. Related: Luciferin.
luciferous (adj.)
"light-bringing, emitting light," 1650s, from Latin lucifer (see Lucifer) + -ous. Figurative use is earliest (1640s) and more common.
lucifugous (adj.)
"shunning the light," 1650s, from Latin lucifugus, from stem of lucere "to shine" (see light (n.)) + stem of fugax "apt to flee, timid," figuratively "transitory, fleeting," from fugere "to flee" (see fugitive).
Lucille
fem. proper name, from French Lucille, diminutive of Latin Lucia (see Lucy).
Lucina
Roman goddess of childbirth, from Latin Lucina, literally "she that brings to the light," fem. of lucinus, from lux (see light (n.)).
Lucite
1937, proprietary name (E.I. DuPont de Nemours and Co., Wilmington, Delaware, U.S.) for a solid, transparent plastic, from Latin luc(i)-, from stem of lucere "to shine" (see light (n.)).
Lucius
masc. proper name; see Lucian.
luck (n.)
late 15c. from early Middle Dutch luc, shortening of gheluc "happiness, good fortune," of unknown origin. It has cognates in Dutch geluk, Middle High German g(e)lücke, German Glück "fortune, good luck." Perhaps first borrowed in English as a gambling term. To be down on (one's) luck is from 1832; to be in luck is from 1900; to push (one's) luck is from 1911. Good luck as a salutation to one setting off to do something is from 1805. Expression better luck next time attested from 1802.
A gentleman was lately walking through St Giles's, where a levelling citizen attempting to pick his pocket of a handkerchief, which the gentleman caught in time, and secured, observing to the fellow, that he had missed his aim, the latter, with perfect sang-froid, answered, "better luck next time master."  [“Monthly Mirror,” London, 1802]
luck (v.)
by 1945, from luck (n.). To luck out "succeed through luck" is American English colloquial, attested by 1946; to luck into (something good) is from 1944. However, lukken was a verb in Middle English (mid-15c.) meaning "to happen, chance;" also, "happen fortunately."
luckily (adv.)
1520s, from lucky + -ly (2).
luckless (adj.)
1560s, from luck (n.) + -less. Related: Lucklessly; lucklessness.
lucky (adj.)
mid-15c., of persons; 1540s, of actions or objects, "likely to bring luck;" from luck + -y (2). Meaning "occurring by chance" is 1590s. Related: Luckier; luckiest; luckiness. Lucky break is attested from 1884 in billiards; 1872 as "failure or break-down which turns out to be fortunate." Lucky Strike as the name of a brand of cigarettes (originally chewing tobacco) popular mid-20c. is said to date from 1871; popular from 1935 when the brand’s maker picked up sponsorship of “Your Hit Parade” on radio.
lucrative (adj.)
early 15c., from Old French lucratif "profitable" and directly from Latin lucrativus "gainful, profitable," from lucratus, past participle of lucrari "to gain," from lucrum "gain, profit" (see lucre). Related: Lucratively; lucrativeness.
lucre (n.)
late 14c., from Latin lucrum "gain, advantage, profit; wealth, riches," from PIE root *lau- "gain, profit" (cognates: Greek apo-lanein "to enjoy," Gothic launs, German lohn "wages, reward," and possibly Sanskrit lotam, lotram "booty"). Filthy lucre (Tit. i:11) is Tyndale's rendering of Greek aischron kerdos.
Lucretia
fem. proper name, from Latin Lucretia (source also of French Lucrèce), fem. of Lucretius, Roman masc. proper name, originally the name of a Roman gens.
lucubrate (v.)
"to work at night," 1620s, from Latin lucubratus, past participle of lucubrare "to work by lamplight" (see lucubration). Literally, "to work by artificial light," hence "to work laboriously."
lucubration (n.)
1590s, "literary work showing signs of too-careful elaboration," from Latin lucubrationem (nominative lucubratio) "nocturnal study, night work," noun of action from past participle stem of lucubrare, literally "to work by artificial light," from stem of lucere "to shine" (see light (n.)).
Lucy
fem. proper name, from French Lucie, from Latin Lucia, fem. of Lucius (see Lucian).
Luddite (n.)
also luddite, 1811, from name taken by an organized band of weavers who destroyed machinery in Midlands and northern England 1811-16 for fear it would deprive them of work. Supposedly from Ned Ludd, a Leicestershire worker who in 1779 had done the same before through insanity (but that story first was told in 1847). Applied to modern rejecters of automation and technology from at least 1961. As an adjective from 1812.
lude (n.)
slang shortening of quaalude, by 1973.
ludic (adj.)
"spontaneously playful," 1940, from French ludique, from Latin ludere "to play" (see ludicrous).
ludicrous (adj.)
1610s, "pertaining to play or sport," from Latin ludicrus, from ludicrum "a sport, game, toy, source of amusement, joke," from ludere "to play," which, with Latin ludus "a game, play," perhaps is from Etruscan, or perhaps from PIE root *leid- "to play." Sense of "ridiculous" is attested from 1782. Related: Ludicrously; ludicrousness.
Ludwig
masc. proper name, from Old High German hlud(o)wig, literally "famous in war," from Proto-Germanic *hluda- "heard of, famous" (see loud) + *wiga "war." Compare Louis.
luff (n.)
c.1200, in sailing, from Old French lof "spar," or some other nautical device, "point of sail," also "windward side," probably from Germanic (compare Middle Dutch lof "windward side of a ship" (Dutch loef), which might also be the direct source of the English word), from Proto-Germanic *lofo (cognates: Old Norse lofi, Gothic lofa "palm of the hand," Danish lab, Swedish labb "paw"), from PIE *lep- "to be flat" (see glove). As a verb from late 14c., from the noun.
Luftwaffe
German air force in World War II era, 1935, from German Luftwaffe, literally "air-weapon," from Luft (see loft).
lug (v.)
late 14c., "to move (something) heavily or slowly," from Scandinavian (compare Swedish lugga, Norwegian lugge "to pull by the hair"); see lug (n.). Related: Lugged; lugging.
lug (n.)
1620s, "handle of a pitcher," from lugge (Scottish) "earflap of a cap, ear" (late 15c.; according to OED, the common word for "ear" in 19c. Scotland), probably from Scandinavian (compare Swedish lugg "forelock," Norwegian lugg "tuft of hair"). The connecting notion is "something that can be gripped and pulled." Applied 19c. to mechanical objects that can be grabbed or gripped. Meaning "stupid fellow" is from 1924; that of "lout, sponger" is 1931, American English. Compare lug-nut (1869), nut closed at one end as a cap.
luge (n.)
kind of small toboggan, 1905, from French luge "small coasting sled," from Savoy dialect, from Medieval Latin sludia "sled" (9c.), perhaps from a Gaulish word from the same root as English sled, slide.
Luger (n.)
type of German automatic pistol, 1904, from Georg Luger (1849-1923), Austrian-born firearms expert.
luggage (n.)
1590s, from lug (v.) "to drag" + -age; so, literally "what has to be lugged about" (or, in Johnson's definition, "any thing of more weight than value"). In 20c., the usual word for "baggage belonging to passengers."
lugger (n.)
"small fishing or coasting boat," 1757, from lugsail (see lug (n.)) or else from Dutch logger "to fish with a dragnet."
lugubriosity (n.)
1839, from Latin lugubris (see lugubrious) + -ity. Sometimes also lugubrosity.
lugubrious (adj.)
c.1600, from Latin lugubris "mournful, pertaining to mourning," from lugere "to mourn," from PIE root *leug- "to break; to cause pain" (cognates: Greek lygros "mournful, sad," Sanskrit rujati "breaks, torments," Lettish lauzit "to break the heart"). Related: Lugubriously; lugubriousness.
lugworm (n.)
c.1600, from lug, probably a Celtic word (the first recorded use is in a Cornwall context) unrelated to lug (n.) or lug (v.) + worm. But OED suggests connection with lug (v.) on the notion of "heavy, clumsy."
luke (adj.)
obsolete except in lukewarm (late 14c.), from Middle English leuk "tepid" (c.1200), of unknown origin; perhaps from Middle Dutch or Old Frisian leuk "tepid, weak," or from Old English hleowe (adv.) "warm," all from Proto-Germanic *khlewaz (see lee).
Luke
masc. proper name, from Latin Lucas (Greek Loukas), contraction of Lucanus literally "of Lucania," district in Lower Italy, home of the Lucani, a branch of the Sabelline race.
lukewarm (adj.)
late 14c., from luke + warm (adj.). Figurative sense of "lacking in zeal" (of persons or their actions) is from 1520s. Related: Lukewarmly; lukewarmness.
lull (v.)
early 14c., lullen "hush to sleep," probably imitative of lu-lu sound used to lull a child to sleep (compare Swedish lulla "to hum a lullaby," German lullen "to rock," Sanskrit lolati "moves to and fro," Middle Dutch lollen "to mutter"). Figurative use from 1570s. Related: Lulled; lulling.
lull (n.)
1650s as the name of a soothing drink, from lull (v.). Meaning "period of quiet in a storm" is from 1815.
lullaby (n.)
1560s, lulley by, from Middle English lollai, lullay, from lullen (see lull (v.)). Second element perhaps from by-by "good-by."
lulu (n.)
"remarkable person or thing," 1886 (first attested in a baseball article from New Orleans, U.S.), of uncertain origin; some suggest a connection to earlier looly "beautiful girl," of unknown origin. But the reference more likely is to Lulu Hurst (1869-1950), the "Georgia Wonder," who was a popular attraction 1883-85 demonstrating her supposed mysterious "force" that allowed her to effortlessly move, with just a light touch, umbrellas and canes held tight by others. She barnstormed the U.S. and, at 15, was, briefly, one of the most famous women in the land. The skeptics soon explained her trick and burst the bubble, but not before her name was used as a word:
Such [musically uneducated persons] start from the avowed or unavowed supposition that the pianist or violinist's art necessitates no higher qualities than does plate-spinning, dancing, or the feats of a Lulu. ["The Hero as Virtuoso," in "London Society magazine," 1883]