Online Etymology Dictionary

larcenous (adj.): "thievish," 1742, from larceny + -ous. Related: Larcenously.
larceny (n.): "theft; wrongful or fraudulent taking of the personal goods of another with felonious intent," late 15c., from Anglo-French larcin (late 13c.), Old French larrecin, larcin "theft, robbery" (11c.), from Latin latrocinium "robbery, freebooting, highway-robbery, piracy," from latro "robber, bandit," also "hireling, mercenary," ultimately from a Greek source akin to latron "pay, hire, wages," from a suffixed form of PIE root *le- (1) "to get" (source also of Greek latreia "worship, service paid to the gods, hired labor," latron "pay, hire," latris "servant, worshipper").

Perhaps with -y (3) added in English or else the word was altered by influence of burglary, felony. Formerly distinguished into grand larceny, involving property valued in excess of a stated amount, and petty larceny.
larch (n.): type of coniferous tree with needle-shaped deciduous leaves, 1548, (William Turner, "Names of Herbes"), from German Lärche, from Middle High German larche, from Old High German *larihha, from Latin larix (genitive laricis), probably a loan-word from an Alpine Gaulish language. De Vaan discourages the suggestion that it could be related to Old Celtic *darik- "oak."

Native to the Alps; the name later was extended to North American species. Compare Danish lærke, Dutch lorken, also from Latin. In French, Old French larice was replaced by mélèze (14c.), a word of uncertain origin.
lard (n.): late 14c. (possibly early 13c.), "rendered fat of a swine," from Old French larde "joint, meat," especially "bacon fat" (12c.), and directly from Latin lardum "lard, bacon, cured swine's flesh" (source also of Spanish, Italian lardo), probably cognate with Greek larinos "fat," laros "pleasing to the taste."
lard (v.): "prepare (meat) for roasting by inserting pieces of salt pork, etc., into it," mid-14c., from Old French larder "to lard, cook with strips of bacon fat" (12c.), from larde "bacon fat" (see lard (n.)). The inserted bacon strip is a lardon or lardoon (from French). Figuratively, of speech or writing, "intersperse with material by way of ornament or improvement," from 1540s. Related: Larded; larding.
lardaceous (adj.): "full of or resembling lard," 1799; see lard (n.) + -aceous.
larder (n.): c. 1300, "supply of salt pork, bacon, and other meats," later in reference to the room for processing and storing such (late 14c.), from Anglo-French larder, Old French lardier "tub for bacon, place for meats," from Medieval Latin lardarium "a room for meats," from Latin lardum "lard, bacon" (see lard (n.)).

Meaning "department of the royal household or of a monastic house in charge of stored meats" is mid-15c. Figurative use, in reference to a "storehouse" of anything, is by 1620s. Surname Lardner "person in charge of a larder" is attested from mid-12c., from Middle English lardyner, from Medieval Latin lardenarius "steward."
lardy (adj.): 1865, from lard (n.) + -y (2). Related: Lardiness.
Lares (n.): Roman tutelary gods and household deities, worshipped in primitive cult rites, Latin, plural of Lar, a word of unknown origin. Infernal, protective of the state and the family, they could be potently evil if offended. Their shrine in the home was a lararium.
larf: representing a colloquial pronunciation of laugh, by 1836. Also see R.
large (adj.): c. 1200, of areas, "great in expanse," of persons, "bountiful, inclined to give or spend freely," from Old French large "broad, wide; generous, bounteous" (12c.), from Latin largus "abundant, copious, plentiful; bountiful, liberal in giving, generous" (source also of Spanish largo "long," Italian largo "wide"), a word of unknown origin.

The modern English meanings "extensive; big in overall size; great in number" emerged 14c. Adjective phrase larger-than-life first attested 1840 (bigger than life is from 1640s). Large-handed has meant both "grasping, greedy" (c. 1600) and "generous, liberal" (1620s); also "having large hands" (1896). Living large is a modern colloquial expression (1994 in African-American vernacular), but large in the sense of "prodigal, lavish" is from late 14c. and, of circumstances, "comfortable, easy" from 1738, and in more recent use Farmer & Henley have it as "impressively, to excess" from 1852.
In mod.Eng., a general designation for considerable magnitude, used instead of great when it is not intended to convey the emotional implication now belonging to that word. [OED]
An older sense of "freedom from prison or restraining influence" is preserved in at large "at (one's) liberty, free from imprisonment or confinement free to move openly" (late 14c.). The phrase, with the meaning "free or at liberty in a general way (without particulars)" is from 1620s; specifically of electors from 1741, American English.
large-mouth (n.): 1884, short for large-mouthed bass (1878); see large (adj.) + mouth (n.).
large-scale (adj.): 1853, from large (adj.) + scale (n.3).
largely (adv.): c. 1200, "liberally, generously, bountifully;" also "in large measure; abundantly," from large + -ly (2). Meaning "extensively, to a great extent" is c. 1400.
largeness (n.): c. 1300, "liberality," also "amplitude, great size," from large + -ness.
larger: comparative of large (q.v.).
largesse (n.): also largess, "willingness to give or spend freely; munificence," c. 1200, from Old French largesse, largece "a bounty, munificence," from Vulgar Latin *largitia "abundance" (source also of Spanish largueza, Italian larghezza), from Latin largus "abundant, large, liberal" (see large). In medieval theology, "the virtue whose opposite is avarice, and whose excess is prodigality" ["Middle English Dictionary"]. For Old French suffix -esse, compare fortress. Related: Largation.
largest (adj.): superlative of large (q.v.).
largish (adj.): 1775, from large (adj.) + -ish.
largo: in music instructions, "slowly and dignified," 1680s, from Italian largo, literally "broad" (see large (adj.)).
lariat (n.): rope or cord used for tying or catching horses, 1832, American English, from Spanish la reata "the rope," from reatar "to tie against," from re- "back" (see re-) + atar "to tie," from Latin aptare "to join," from aptus "fitted" (see apt). Compare lasso.
lark (n.1): songbird of the Old World, early 14c., earlier lauerche (c. 1200), from Old English lawerce (late Old English laferce), from Proto-Germanic *laiw(a)rikon (source also of Old Saxon lewerka, Frisian liurk, Old Norse lævirik, Dutch leeuwerik, German Lerche), a word of unknown origin.

Old English and Old Norse forms suggest a contracted compound, perhaps meaning "treason-worker," but "nothing is known in folklore to account for such a designation" [OED]. Noted for its early song and high flying (in contrast to its low nest). When the sky falls, we shall catch larks was an old proverb mocking foolish optimism.
lark (n.2): "spree, frolic, merry adventure," 1811, slang, of uncertain origin. Possibly a shortening of skylark (1809), sailors' slang for "play rough in the rigging of a ship" (larks were proverbial for high-flying). Or perhaps it is an alteration of English dialectal or colloquial lake/laik "to play, frolic, make sport" (c. 1300, from Old Norse leika "to play," from PIE *leig- (3) "to leap") with intrusive -r- common in southern British dialect. The verb lake, considered characteristic of Northern English vocabulary, is the opposite of work but lacks the other meanings of play. As a verb, from 1813. Related: Larked; larking.
lark (v.): "to play tricks, frolic," 1813; see lark (n.2). Related: Larked; larking.
larking (n.): "fun, frolicking," 1813, verbal noun from lark (v.); also see lark (n.2).
larkspur (n.): type of plant, 1570s, from lark (n.) + spur (n.); so called from resemblance of the calyx and petals to the bird's long, straight hind claw.
larky (adj.): "frolicsome," 1841, from lark (n.2) + -y (2). Related: Larkiness.
larrikin (n.): "street tough, rowdy," 1868, Australia and New Zealand, of unknown origin; perhaps somehow from the masc. proper name Larry.
larrup (v.): "to beat, thrash," 1823, of unknown origin, possibly related to Dutch larpen "to thrash." First mentioned as a Suffolk dialect word.
Larry: masc. proper name, often a familiar form of Lawrence. Expression happy as Larry attested from 1887, of unknown signification.
larva (n.): 1650s, "a ghost, specter, disembodied spirit" (earlier as larve, c. 1600), from Latin larva (plural larvae), earlier larua "ghost, evil spirit, demon," also "mask," a word from Roman mythology, of unknown origin; de Vaan finds a possible derivation from Lar "tutelary god" (see Lares) "quite attractive semantically."

Crowded out in its original sense by the zoological use (1768) which began with Linnaeus, who applied the word to immature forms of animals that do not resemble, and thus "mask," the adult forms. On the double sense of the Latin word, Carlo Ginzburg, among other observers of mythology and folklore, has commented on "the well-nigh universal association between masks and the spirits of the dead."
larvae (n.): plural of larva (q.v.).
larval (adj.): 1650s, "pertaining to ghosts," from Latin larvalis, from larva (see larva). Zoological sense, "pertaining to a larva," is from 1848. In recent times, larvate (adj.) has been used for "masked, clothed as if with a mask" (1846).
larvi-: word-forming element in zoology, from comb. form of larva (q.v.).
larvivorous (adj.): "feeding on grubs and caterpillars," 1863; see larva + -vivorous.
laryngeal (adj.): 1795 in anatomy, "of or pertaining to the larynx," from medical Latin laryngeus (from Greek larynx, genitive laryngos, "the upper windpipe;" see larynx) + English -al (1). Sometimes spelled laryngal (1834). As a noun, in linguistics, from 1921.
laryngitis (n.): "inflammation of the larynx," 1818, Medical Latin, from comb. form of larynx (q.v.) + -itis "inflammation." Related: Laryngitic (1847).
larynx (n.): "cartilaginous cavity in the upper windpipe where vocal sounds are made," 1570s, from Middle French larynx (16c.), via medical Latin, from Greek larynx (genitive laryngos) "the upper windpipe," which is probably from laimos "throat" (a word of uncertain etymology) but influenced by pharynx "throat, windpipe" (see pharynx).
lasagna (n.): "pasta cut in long, wide strips; a dish made from this," 1760 (as an Italian word in English), from Italian (plural is lasagne), from Vulgar Latin *lasania, from Latin lasanum "a cooking pot," from Greek lasanon "pot with feet, trivet." Sometimes nativized as lasagne.
lascar (n.): 1620s, "East Indian sailor," from Portuguese lachar, from Hindi lashkari "soldier, native sailor," from lashkar "army, camp," from Persian lashkar. Compare Arabic al-'askar "the army," which is perhaps from Persian. Later in Anglo-Indian the word appears in the sense "native tent-pitcher, camp follower, or regimental servant" (1798).
lascivious (adj.): mid-15c., "lustful, inclined to lust," from Middle French lascivieux or directly from Late Latin lasciviosus (used in a scolding sense by Isidore and other early Church writers), from Latin lascivia "lewdness, playfulness, fun, frolicsomeness, jolity," from lascivus "lewd, playful, undesigned, frolicsome, wanton."

This is from PIE *las-ko-, from the root *las- "to be eager, wanton, or unruly" (source also of Sanskrit -lasati "yearns," lasati "plays, frolics," Hittite ilaliya- "to desire, covet," Greek laste "harlot," Old Church Slavonic laska "flattery," Slovak laska "love," Russian lasyj "greedy, eager, affectionate," Old Irish lainn "greedy, eager," Gothic lustus, Old English lust "lust").

Meaning "tending to excite lust" is from 1580s. Related: Lasciviously. In 17c. also with a verbal form, lasciviate, now obsolete.
lasciviousness (n.): 1590s, from lascivious + -ness. An earlier noun form was lascivity (c. 1500); a later one was lascivency (1660s).
laser (n.): 1960, acronym for "light amplification by stimulated emission of radiation," on pattern of maser (1955). A corresponding verb, lase, was coined by 1962. Related: Lasered; lasering. Laser disc recorded from 1980. Earlier laser was the name of a type of gum-resin from North Africa used medicinally (1570s), from Latin; still earlier it was an Old English and Middle English name for some weed, probably cockle.
lash (n.): c. 1300, las "a blow, a stroke," later "flexible part of a whip" (late 14c.), possibly imitative; compare lash (v.1), which might be the immediate source of this. Century Dictionary says Irish lasg "a lash, whip, whipping" is of English origin. The lash "punishment by flogging" is from 1690s.
lash (v.2): "to tie or bind," as with rope or cord, 1620s, originally nautical, from Middle French lachier, from Old French lacier "to lace on, fasten with laces; entrap, ensnare" (see lace (v.)). Related: Lashed; lashing.
lash (v.1): c. 1300, "to deal a blow;" later "to strike with a whip, beat with a lash" (late 14c.), possibly imitative. To lash out "to strike out violently" (originally of horses) is from 1560s and preserves the older sense. Related: Lashed; lashing.
lashing (n.): "a beating, flogging," c. 1400, verbal noun from lash (v.1).
lass (n.): "young woman, girl," c. 1300, probably from a Scandinavian source akin to Old Swedish løsk kona "unmarried woman" [OED], but other sources say perhaps related to Old Norse löskr "idle, weak," West Frisian lask "light, thin." Liberman suggests Old Danish las "rag," and adds, "Slang words for 'rag' sometimes acquire the jocular meaning 'child' and especially 'girl.'" "Used now only of mean girls" [Johnson, who has an entry for Shakespeare's lass-lorn "forsaken by his mistress"]. Paired with lad since early 15c.
Lassa: 1970 in reference to a febrile disease of tropical Africa, from Lassa, name of a village in northeastern Nigeria.
lassie (n.): "small girl, young girl," by 1725, Scottish diminutive of lass (n.) with -ie. Scott also has lassock (1816).