Online Etymology Dictionary

lagoon (n.): 1670s, lagune, earlier laguna (1610s), from French lagune or directly from Italian laguna "pond, lake," from Latin lacuna "pond, hole," from lacus "pond" (see lake (n.1)). Originally in reference to the region of Venice; applied 1769 (by Capt. Cook) to the lake-like stretch of water enclosed in a South Seas atoll. Also cf. -oon.
lai: see lay (n.).
laic (adj.): 1560s, from French laïque (16c.), from Late Latin laicus, from Greek laikos "of or belonging to the people," from laos "people" (see lay (adj.)).
laid: past tense and past participle of lay (v.). Laid-up "injured, sick," originally was a nautical term (1769) describing a ship moored in harbor. Laid off "temporarily unemployed" is from 1916. Get laid "have sex" (with someone) attested from 1952, U.S. slang. Laid-back "relaxed" is first attested 1973, perhaps in reference to the posture of highway motorcyclists. Laid up "incapacitated" originally was of ships.
laidly (adj.): c.1300, Scottish and northern English variant of loathly "hideous, repulsive" (see loath).
lain: past participle of lie (v.2).
lair (n.): Old English leger "bed, couch, grave; act or place of lying down," from Proto-Germanic *legraz (cf. Old Norse legr "grave," also "nuptials" ("a lying down"); Old Frisian leger "situation," Old Saxon legar "bed," Middle Dutch legher "act or place of lying down," Dutch leger "bed, camp," Old High German legar "bed, a lying down," German Lager "bed, lair, camp, storehouse," Gothic ligrs "place of lying"), from PIE *legh- "to lie, lay" (see lie (v.2)). Meaning "animal's den" is from early 15c.
laird (n.): mid-15c. (mid-13c. as a surname), Scottish and northern England dialectal variant of lord, from Middle English laverd (see lord). Related: Lairdship.
laissez-faire: laissez faire, 1822, French, literally "let (people) do (as they think best)," from laissez, imperative of laisser "to let, to leave" (from Latin laxare, from laxus "loose;" see lax) + faire "to do" (from Latin facere; see factitious). From the phrase laissez faire et laissez passer, motto of certain 18c. French economists, chosen to express the ideal of government non-interference in business and industry.
laity (n.): "body of people not in religious orders," early 15c., from Anglo-French laite, from lay (adj.) + -ity.
lake (n.1): "body of water," early 12c., from Old French lack and directly from Latin lacus "pond, lake," also "basin, tank," related to lacuna "hole, pit," from PIE *laku- (cf. Greek lakkos "pit, tank, pond," Old Church Slavonic loky "pool, puddle, cistern," Old Irish loch "lake, pond"). The common notion is "basin." There was a Germanic form of the word, which yielded cognate Old Norse lögr "sea flood, water," Old English lacu "stream," lagu "sea flood, water," leccan "to moisten" (see leak). In Middle English, lake, as a descendant of the Old English word, also could mean "stream; river gully; ditch; marsh; grave; pit of hell," and this might have influenced the form of the borrowed word. The North American Great Lakes so called from 1660s.
lake (n.2): "deep red coloring matter," 1610s, from French laque (see lac), from which it was obtained.
laker (n.): used of people or things associated in various ways with a lake or lakes, including tourists to the English Lake country (1798); the poets (Wordsworth, etc.) who settled in that region (1814); boats on the North American Great Lakes (1887), and a person whose work is on lakes (1838); see lake (n.1). The U.S. professional basketball team began 1947 as the Minneapolis Lakers, where the name was appropriate; before the 1960-1 season it moved to Los Angeles, but the name was kept.
Lakshmi: Hindu goddess of beauty, from Sanskrit lakshmi "mark, fortue, riches, beauty."
lallygag (v.): 1862; see lollygag. Related: Lallygagged; lallygagging.
lam (n.): "flight," as in on the lam, 1897, from a U.S. slang verb meaning "to run off" (1886), of uncertain origin, perhaps somehow from the first element of lambaste, which was used in British student slang for "beat" since 1590s; if so, it would give the word the same etymological sense as the slang expression beat it.
lama (n.): "Buddhist priest of Mongolia or Tibet," 1650s, from Tibetan blama "chief, high priest," with silent b-. Related: Lamasery.
Lamarckian (adj.): 1846, pertaining to French botanist and zoologist J.B.P. Lamarck (1744-1829), especially his view that the process of evolution includes the inheritance of acquired characteristics.
Lamaze: childbirth technique, developed 1940s by French obstetrician Dr. Fernand Lamaze (1891-1957) and named for him.
lamb (n.): Old English lamb "lamb," from Proto-Germanic *lambaz (cf. Old Norse, Old Frisian, Gothic lamb, Middle Dutch, Dutch lam, Middle High German lamp, German Lamm "lamb"). Common to the Germanic languages, but with no certain cognates outside them. Old English plural was lomberu. Applied to persons (especially young Church members, gentle souls, etc.) from late Old English. Also sometimes used ironically for cruel or rough characters (e.g. Kirke's Lambs in wars of 1684-86). Lamb's-wool (adj.) is from 1550s.
lambada (n.): "sensual Brazilian dance," 1988, from Portuguese, said in some sources to be literally "a beating, a lashing." But others connect it ultimately to Latin lumbus "loin."
lambaste (v.): 1630s, from lam (1590s, ultimately from a Scandinavian source, cf. Old Norse lemja "to beat, to lame") + baste "to thrash" (see baste). Related: Lambasted; lambasting.
lambda (n.): Greek letter name, from a Semitic source akin to Hebrew lamedh.
lambency (n.): 1817, from lambent + -cy.
lambent (adj.): 1640s, from figurative use of Latin lambentem (nominative lambens), present participle of lambere "to lick," from PIE root *lab-, indicative of smacking lips or licking (cf. Greek laptein "to sip, lick," Old English lapian "to lick, lap up, suck;" see lap (v.1)).
Lambert: masc. proper name, from French, from German Lambert, from Old High German Lambreht, from lant "land" + beraht "bright." Old English cognate was Landbeorht. The popularity of the name from 12c. is probably due to immigration from Flanders, where St. Lambert of Maestricht was highly venerated. Attested as a surname from mid-12c.
Lambeth: used metonymically for "Church of England, Archbishop of Canterbury," 1859, from the archbishop's palace in Lambeth, a South London borough. The Lambeth Walk was a Cockney song and dance, popularized in Britain 1937 in the revue "Me and my Gal," named for a street in the borough. The place name is Old English lambehyðe, "place where lambs are embarked or landed."
lambic (n.): "strong Belgian beer," 1829, related to French alambic "a still" (see alembic).
lambkin (n.): mid-13c., as a surname, from lamb + diminutive suffix -kin.
lambskin (n.): mid-14c., from lamb + skin (n.).
lame (n.): "silk interwoven with metallic threads," 1922, from French lame, earlier "thin metal plate (especially in armor), gold wire; blade; wave (of the sea)," from Middle French lame, from Latin lamina, lamna "thin piece or flake of metal."
lame (adj.): Old English lama "crippled, lame; paralytic, weak," from Proto-Germanic *lamon (cf. Old Norse lami, Dutch and Old Frisian lam, German lahm "lame"), "weak-limbed," literally "broken," from PIE root *lem- "to break; broken," with derivatives meaning "crippled" (cf. Old Church Slavonic lomiti "to break," Lithuanian luomas "lame"). In Middle English, "crippled in the feet," but also "crippled in the hands; disabled by disease; maimed." Sense of "socially awkward" is attested from 1942. Noun meaning "crippled persons collectively" is in late Old English.
lame (v.): "to make lame," c.1300, from lame (adj.). Related: Lamed; laming.
lame duck (n.): 1761, "any disabled person or thing;" especially Stock Exchange slang for "defaulter."
A lame duck is a man who cannot pay his differences, and is said to waddle off. [Thomas Love Peacock, "Gryll Grange," 1861]
Sometimes also in naval use for "an old, slow ship." Modern sense of "public official serving out term after an election" is recorded by 1878 in American English, from an anecdote published in that year of President Lincoln, who is alleged to have said, "[A] senator or representative out of business is a sort of lame duck. He has to be provided for."
lame-brain (n.): 1921, from lame (adj.) + brain (n.).
lamely (adv.): 1590s, from lame (adj.) + -ly (2).
lameness (n.): 1520s, from lame (adj.) + -ness.
lament (v.): mid-15c., back-formation from lamentation or else from Middle French lamenter "to moan, bewail" (14c.) and directly from Latin lamentari, from lamentum (see lamentation). Related: Lamented; lamenting.
lament (n.): 1590s, from Middle French lament and directly from Latin lamentum (see lamentation).
lamentable (adj.): c.1400, from Middle French lamentable and directly from Latin lamentabilis "full of sorrow, mournful, lamentable," from lamentari "to lament" (see lamentation). Related: Lamentably.
lamentation (n.): late 14c., from Old French lamentacion and directly from Latin lamentationem (nominative lamentatio) "wailing, moaning, weeping," noun of action from past participle stem of lamentari "to wail, moan, weep, lament," from lamentum "a wailing," from PIE root *la- "to shout, cry," probably ultimately imitative. Replaced Old English cwiþan.
Lamentations (n.): Biblical book, late 14c., short for Lamentations of Jeremiah, from Latin Lamentationes, translating Greek Threnoi (see lamentation).
lamented (adj.): "mourned for," 1610, from past participle of lament (v.).
lamia (n.): late 14c., from Latin lamia, from Greek lamia "female vampire," literally "swallower, lecher," from laimos "throat, gullet." Probably cognate with Latin lemures "spirits of the dead" (see lemur). Used in early translations of the Bible for screech owls and sea monsters. Sometimes also, apparently, mermaids.
Also kynde erreþ in som beestes wondirliche j-schape, as it fareþ in a beest þat hatte lamia, þat haþ an heed as a mayde & body as a grym fissche[;] whan þat best lamya may fynde ony man, first a flatereþ wiþ hym with a wommannes face and makeþ hym ligge by here while he may dure, & whanne he may noferþere suffice to here lecherye þanne he rendeþ hym and sleþ and eteþ hym. [John of Trevisa, translation of Bartholomew de Glanville's "De proprietatibus rerum," 1398]
laminate (v.): 1660s, "to beat or roll into thin plates," from Latin lamina "thin piece of metal or wood, thin slice, plate, leaf, layer," of unknown origin. Many modern senses are from the noun meaning "an artificial thin layer" (1939), especially a type of plastic adhesive. Related: Laminated; laminating.
lamination (n.): "any layer of laminated substance," 1670s, noun of state from laminate. Meaning "process of manufacturing laminated products" is from 1945.
Lammas (n.): Aug. 1 harvest festival with consecration of loaves, Old English hlafmæsse, literally "loaf mass," from hlaf (see loaf (n.)) + mæsse (see mass (n.2)). Altered by influence of lamb (and occasionally spelled lamb- in 16c.-17c.).
lamp (n.): c.1200, from Old French lampe "lamp, lights" (12c.), from Latin lampas "a light, torch, flambeau," from Greek lampas "torch, lamp, beacon, meteor, light," from lampein "to shine," from nasalized form of PIE root *lap- "to shine" (cf. Lithuanian lope "light," Old Irish lassar "flame"). Replaced Old English leohtfæt "light vessel." To smell of the lamp "be a product of laborious night study" is from 1570s.
lamp-black (n.): pigment made from pure, fine carbon, originally from the soot produced by burning oil in lamps, 1590s, see lamp.
lamp-post (n.): also lamppost, 1731, from lamp + post (n.1).