Online Etymology Dictionary

L: twelfth letter, Roman form of Greek lambda, which is from the Semitic lamed. The shape of the Roman letter is an early one in Greek, adopted in Italic before it was superseded in Greek by the inverted form which became the Greek lambda. In some words (ladder, lady, laughter, leap, listen, lid) it represents Old English hl-. As "building or extension in the shape of an L" from 1843. As an "alphabetic abbreviation" [OED] of elevated railway, from 1881 (compare el). The Three Ls in nautical navigation were "lead" (for sounding), "latitude" and "lookout."
L.A.: abbreviation for Los Angeles, attested from 1949.
l.s.d.: abbreviation of British currency units, 1853, from first letters of Late Latin librae (see Libra), solidi (see solidus), denarii (see denarius), Roman equivalent of "pounds, shillings, pence." Hence LSDeism "worship of money" (1892).
la (1): musical note (sixth note of the diatonic scale), early 14c., see gamut. It represents the initial syllable of Latin labii "of the lips." In French and Italian it became the name of the musical note A, which is the sixth of the natural scale (C major).
la (2): fem. form of the French definite article, used in English in certain phrases and sometimes added ironically to a woman's name with a suggestion of "prima donna" (OED examples begin 1860s). See le.
la (3): Anglo-Saxon interjection of mild wonder or surprise, or grief; "oh, ah, indeed, verily."
La Tene (adj.): 1882 in archaeology in reference to La Tène, district at the end of Lake Neuchâtel in Switzerland, where after c. 1860 relics were found from a prehistoric culture that dominated central Europe c. 3c. B.C.E.
la-di-da (interj.): mocking affected gentility, 1874, a derisive imitation of the "swell" way of talking. Compare lardy-dardy (1859).
la-la: syllables used to make nonsense refrains in songs; compare Old English la, a common exclamation; but la-la is imitative of babbling speech in many languages: Greek lalage "babble, prattle," Sanskrit lalalla as an imitation of stammering, Latin lallare "to sing to sleep, lull," German lallen "to stammer," Lithuanian laluoti "to stammer."
La-Z-Boy: brand of recliner chair, 1929, Floral City Furniture Co., Monroe, Michigan, U.S. According to company lore, chosen from names submitted in a contest. See lazy + boy.
lab (n.): shortened form of laboratory, 1895.
labarum (n.): the imperial standard adopted by Constantine, from Greek labaron, which is of unknown origin.
labefaction (n.): "process of shaking; downfall, overthrow," 1610s, noun of action from Latin labefactus, past participle of labefacere "to cause to totter, shake," literally and figuratively; also "to overthrow," from labi "to slip, slide, sink, fall; decline, go to ruin" (see lapse (n.)) + facere "to make, do" (see factitious).

Alternative labefactation (from Latin labefactitionem "a shaking, loosening," noun of action from past participle stem of labefacere) is attested from 1775. As a verb, labefact is from 1540s, labefy 1620s, labefactate from 1650s.
label (n.): c. 1300, "narrow band or strip of cloth" (oldest use is as a technical term in heraldry), from Old French label, lambel, labeau "ribbon, fringe worn on clothes" (13c., Modern French lambeau "strip, rag, shred, tatter"). This is perhaps, with a diminutive suffix, from Frankish *labba or some other Germanic source (such as Old High German lappa "flap"), from Proto-Germanic *lapp-, forming words for loose cloth, etc. (see lap (n.1)).

Meanings "dangling strip of cloth or ribbon used as an ornament in dress," also "strip attached to a document to hold a seal" both are from early 15c. General meaning "tag, sticker, slip of paper" affixed to something to indicate its nature, contents, destination, etc. is from 1670s. Hence "circular piece of paper in the center of a gramophone record," containing information about the recorded music (1907), which led to the meaning "a recording company" (1947).
label (v.): "to affix a label to," c. 1600, see label (n.); figurative sense of "to categorize" is from 1853. Related: Labeled; labeling; labelled; labelling.
labia (n.): in anatomy and zoology, "lips or lip-like parts," a Modern Latin use of Latin labia "lips," plural of labium "lip" (see lip (n.)). Specifically as "the folds on either side of the vulva" (labia pudendi) from 1630s; further classified as labia majora (the outer folds, 1813; the singular is labium majus) and labia minora (inner folds, 1781; the singular is labium minus). The lips of the mouth are labium superior (upper) and labium inferiore (lower).
labial (adj.): "pertaining to the lips," 1590s, from Medieval Latin labialis "having to do with the lips," from Latin labium "lip" (see lip (n.)). The noun meaning "a labial sound" (one accomplished by complete closure of the lips) is from 1660s, from the adjective in this sense (1590s). Related: Labially.
labialize (v.): 1856, from labial + -ize. Related: Labialized; labializing.
labiate (adj.): "having a lip or lip-like part," 1706, from Modern Latin labiatus "lipped," from Latin labium "lip" (see lip (n.)).
labile (adj.): mid-15c., "prone to lapse," from Latin labilis, from labi "to slip" (see lapse (n.)). Hence, in chemistry, "prone to undergo displacement" (c. 1600).
labio-: word-forming element in medical use since 17c., taken as a comb. form of Latin labium "lip" (see lip (n.)).
labium (n.): "lip or lip-like part," 1590s, plural labia (q.v.), from Latin labium "lip" (see lip (n.)).
labonza (n.): "belly," 1943, American English slang, probably from dialectal pronunciation of Italian la pancia "the belly," with the definite article absorbed, from Latin pantex (genitive panticis) "belly" (see paunch).
labor (n.): c. 1300, "a task, a project" (such as the labors of Hercules); later "exertion of the body; trouble, difficulty, hardship" (late 14c.), from Old French labor "toil, work, exertion, task; tribulation, suffering" (12c., Modern French labeur), from Latin labor "toil, exertion; hardship, pain, fatigue; a work, a product of labor," a word of uncertain origin. Some sources venture that it could be related to labere "to totter" on the notion of "tottering under a burden," but de Vaan finds this unconvincing. The native word is work.

Meaning "body of laborers considered as a class" (usually contrasted to capitalists) is from 1839; for the British political sense see labour. Sense of "physical exertions of childbirth" is attested from 1590s, short for labour of birthe (early 15c.); the sense also is found in Old French, and compare French en travail "in (childbirth) suffering" (see travail). Labor Day was first marked 1882 in New York City. The prison labor camp is attested from 1900. Labor-saving (adj.) is from 1776. Labor of love is by 1797.
labor (v.): late 14c., "perform manual or physical work; work hard; keep busy; take pains, strive, endeavor" (also "copulate"), from Old French laborer "to work, toil; struggle, have difficulty; be busy; plow land," from Latin laborare "to work, endeavor, take pains, exert oneself; produce by toil; suffer, be afflicted; be in distress or difficulty," from labor "toil, work, exertion" (see labor (n.)).

The verb in modern French, Spanish, and Portuguese means "to plow;" the wider sense being taken by the equivalent of English travail. Sense of "endure pain, suffer" is early 15c., especially in phrase labor of child (mid-15c.). Meaning "be burdened" (with trouble, affliction, etc., usually with under) is from late 15c. The transitive senses have tended to go with belabor. Related: Labored; laboring.
laboratory (n.): c. 1600, "room or building set apart for scientific experiments," from Medieval Latin laboratorium "a place for labor or work," from Latin laboratus, past participle of laborare "to work" (see labor (v.)). Figurative use by 1660s.
labored (adj.): also laboured, "learned," mid-15c., past participle adjective from labor (v.). Meaning "done with much labor" is from c. 1600.
laborer (n.): mid-14c., "manual worker," especially an unskilled one, agent noun from labor (v.). Meaning "member of the working class, member of the lowest social rank" is from c. 1400 (compare labour).
laborious (adj.): late 14c., "hard-working, industrious," from Old French laborios "arduous, wearisome; hard-working" (12c., Modern French laborieux), from Latin laboriosus "toilsome, wearisome, troublesome," also "inclined to labor, industrious," from labor "toil, exertion" (see labor (n.)). Meaning "costing much labor, burdensome" is from early 15c.; meaning "resulting from hard work" is mid-15c. Related: Laboriousness.
laboriously (adv.): early 15c., "slowly and with difficulty," from laborious + -ly (2). Meaning "earnestly, strongly" is from c. 1500.
labour: chiefly British English spelling of labor (q.v.); for spelling, see -or. With capital L-, short for "the British Labour Party," it is attested from 1892; the party name itself is from 1886.
labourer (n.): chiefly British English spelling of laborer; for suffix, see -or.
Labrador: large province of eastern Canada, probably from Portuguese Lavrador.
[Labrador] is not used in Cartier's narratives, though it appears in the title of the 1598 edition of his first narrative. It is supposed to have been added by the translator. There are, at least, six theories as to the origin of this word. [W.F. Ganong, "The Cartography of the Gulf of St. Lawrence," 1887]
He lists as "The generally accepted and altogether probable one" that "it was originally 'Terra Laboratoris,' land of the laborer because Cortereal brought fifty men thence to Europe, who were described as well fitted for slaves. This is sustained by all the evidence of old maps." Gasper Cortereal was a Portuguese navigator who explored the coast for the Portuguese crown in 1500 and brought home captives. He returned for more in 1501, but was never heard from again. But a Portuguese map of 1520 has the name Lavrador applied to Greenland, while the coast of Labrador and Newfoundland is called Bacalhaos, which is "codfish" in Basque. Another theory [Room] is that the sense of the name is "landholder" and is a reference to 15c. Portuguese explorer João Fernandes, who was a landholder in the Azores. The breed of retriever dog so called from 1815. Related: Labradorian.
labret (n.): ornament inserted into a lip, 1843 (first reference is to Eskimo men), from Latin labrum "a lip" (cognate with labium "lip;" see lip (n.)) + -et.
labrum (n.): lip or lip-like part, 1816, in various anatomical and zoological uses, from Latin labrum "a lip," cognate with labium "lip" (see lip (n.)). The same word is also noted in Middle English as the name of some herb.
laburnum (n.): small, leguminous tree native to the Alps, 1570s, from Latin laburnum (Pliny), a word of unknown origin; perhaps from Etruscan.
labyrinth (n.): c. 1400, laberynthe (late 14c. in Latinate form laborintus) "labyrinth, maze, great building with many corridors and turns," figuratively "bewildering arguments," from Latin labyrinthus, from Greek labyrinthos "maze, large building with intricate passages," especially the structure built by Daedelus to hold the Minotaur, near Knossos in Crete, a word of unknown origin.

Apparently from a pre-Greek language; traditionally connected to Lydian labrys "double-edged axe," symbol of royal power, which fits with the theory that the original labyrinth was the royal Minoan palace on Crete. It thus would mean "palace of the double-axe." But Beekes finds this "speculative" and compares laura "narrow street, narrow passage, alley, quarter," also identified as a pre-Greek word. Used in English for "maze" early 15c., and in figurative sense of "confusing state of affairs" (1540s). As the name of a structure of the inner ear, the essential organ of hearing, from 1690s.
labyrinthine (adj.): 1630s; see labyrinth + -ine (1). Figurative use by 1831. Earlier adjective forms were labyrinthian/labyrinthean (1580s), labyrinthial (1540s), labyrinthical (1620s), labyrinthic (1640s).
lac (n.): "red resinous substance," 1550s, perhaps immediately from Middle French lacce, displacing or absorbing earlier lacca (early 15c.), from Medieval Latin lacca. All these are from Persian lak, from Hindi lakh (Prakrit lakkha), from Sanskrit laksha "red dye," which is of uncertain origin.

According to Klein, it means literally "one hundred thousand" and is a reference to the insects that gather in great numbers on the trees and create the resin. But others say lakh is perhaps an alteration of Sanskrit rakh, from an IE root word for "color, dye" [Watkins]. Still another guess is that Sanskrit laksha is related to English lax, lox "salmon," and the substance perhaps was so called from being somewhat the color of salmon [Barnhart]. Also see shellac (n.).
lace (n.): early 13c., laz, "cord made of braided or interwoven strands of silk, etc.," from Old French laz "a net, noose, string, cord, tie, ribbon, or snare" (Modern French lacs), from Vulgar Latin *lacium, from Latin laqueum (nominative laqueus) "a noose, a snare" (source also of Italian laccio, Spanish lazo, English lasso), a trapping and hunting term, probably from Italic base *laq- "to ensnare" (compare Latin lacere "to entice").

Later also "net, noose, snare" (c. 1300); and "piece of cord used to draw together the edges of slits or openings in an article of clothing" (late 14c., as preserved in shoelace). In Middle English it mostly had the sense "cord, thread," especially for tying or binding. It was used of fishing lines and perhaps the gallows rope, crossbeams in architecture, and the net Vulcan used to catch Venus in adultery. Death's lace was the icy grip of Death, and Love's lace was a binding love.

From 1540s as "ornamental cord or braid," hence the meaning "fabric of fine threads in a patterned ornamental open net" (1550s), which soon became the main meaning of the English word. "Century Dictionary" (1902) describes by name 87 varieties. As an adjective, lace-curtain "middle class" (or lower-class with middle-class pretensions), often used in reference to Irish-Americans, is attested by 1928.
lace (v.): c. 1200, "fasten (clothing, etc.) with laces and ties," from Old French lacier "entwine, interlace, fasten with laces, lace on; entrap, ensnare," from laz "net, noose, string, cord" (see lace (n.)). From early 14c. as "tighten (a garment) by pulling its laces." From 1590s as "to adorn with lace;" the meaning "to intermix (coffee, etc.) with a dash of liquor" (1670s) originally also was used of sugar, and comes via the notion of "to ornament or trim," as with lace. Meaning "beat, lash, mark with the lash" is from 1590s, from the pattern of streaks. Related: Laced; lacing. Laced mutton was "an old word for a whore" [Johnson].
lace-up (adj.): 1831, originally of boots, from the verbal phrase, from lace (v.) + up (adv.).
lace-wing (n.): also lacewing, type of insect, 1847; see lace (n.) + wing (n.). Earlier was lace-winged fly (1826), and the shorter for might be from this.
Lacedaemonian (adj.): "pertaining to Sparta," 1709, from Latin Lacedaemonius, from Greek Lakedaimonios, from Lakedaimon, an ancient Greek name for Sparta as the capital of Lakonia (see laconic). From 1713 as a noun.
laceman (n.): dealer in laces, 1660s, from lace (n.) + man.
lacerate (v.): "to tear roughly," early 15c., from Latin laceratus, past participle of lacerare "tear to pieces, mangle," figuratively, "to slander, censure, abuse," from lacer "torn, mangled," from PIE root *lek- "to rend, tear" (source also of Greek lakis "tatter, rag," lakizein "to tear to pieces;" Latin lacinia "flap of a garment," lancinare "to pierce, stab;" Russian lochma "rag, tatter, scrap;" Albanian l'akur "naked"). Figurative sense in English is from 1640s. Related: Lacerated; lacerating.
laceration (n.): 1590s, "act of lacerating;" 1630s, "breach or rend made by tearing;" from Middle French lacération, from Latin lacerationem (nominative laceratio) "a tearing, rending, mutilation," noun of action from past participle stem of lacerare "tear to pieces, mangle; slander, abuse" (see lacerate).
lacertine (adj.): "lizard-like," 1841, from Latin lacerta (see lizard). Other adjectives from the early years of dinosaur paleontology were lacertian (1841), lacertilian (1848). In decorative arts, lacertine work (1854) consists of intertwined serpents.
lacey: see lacy.
laches (n.): "negligence in performance of legal duty," 1570s, earlier simply "slackness, negligence, want of zeal" (late 14c.), from Anglo-French laches, Old French lachesse "lawlessness, remissness," from Old French lasche "lax, remiss" (Modern French lâche), verbal adjective from lascher, from Vulgar Latin *lascare, classical laxare "to slacken, relax," from laxus "loose; yielding; indulgent" (see lax). Compare riches.