Online Etymology Dictionary

latke (n.): "pancake made with grated potatoes," 1925, American English, from Yiddish, from Russian latka "pastry," said to mean literally "a patch," but by Watkins traced to Greek elaia "olive."
latration (n.): "barking," 1620s, noun of action from Latin latrare "to bark."
latrine (n.): c. 1300, laterin "a privy," probably from Latin latrina, latrinum, a contraction of lavatrina "washbasin, washroom," from lavatus, past participle of lavare "to wash" (from PIE root *leu(e)- "to wash;" see lave) + -trina, suffix denoting "workplace." The word's reappearance in 1640s probably is a re-borrowing from French. In modern use, especially of a public privy of a camp, barracks, college, hospital, etc. Latrine rumor "baseless gossip" (of the kind that spreads in conversations in latrines) is military slang, first recorded 1918.
latte (n.): espresso coffee with milk, by 1990, short for caffè latte, which is an Italian expression meaning literally "milk coffee," from Latin lac (genitive lactis) "milk" (see lacto-). Compare cafe au lait.
latter (adv.): Old English lator, "more slowly," comparative of late. From c. 1200 as "at a later time." Old English also had lætemest (adv.) "lastly, finally."
latter (adj.): Old English lætra "slower," comparative of læt "late" (see late (adj.)). Meaning "belonging to a subsequent period" is from c. 1200. Sense of "that has been mentioned second of two or last" is first recorded 1550s.

In modern use the more common word is later, which is from mid-15c. and is perhaps a new formation or a variant of this word. Latter survives mostly in the phrase the latter, which, with the former is used to avoid repetition (but sometimes incorrectly, when more than two are involved).
latter-day (adj.): "belonging to recent times," 1842; see latter (adj.). Originally in Latter-day Saints, the Mormon designation for themselves.
latterly (adv.): 1734, from latter (adj.) + -ly (2). Called by Johnson [1755] "a low word lately hatched." Related: Lattermost.
lattice (n.): "work with open spaces formed by crossing or interlacing of laths, bars, etc.," c. 1300, from Old French latiz "lattice," from late "lath, board, plank, batten" (Modern French latte), from Frankish or some other Germanic source, such as Old High German latta "lath" (see lath). As a verb from early 15c. Related: Latticed.
latticework (n.): also lattice-work, late 15c., from lattice + work (n.).
Latvia: Baltic nation, first independent in 1918, named for its inhabitants, Latvian Latvji, whose ancient name is of unknown origin. In English, the people name was Lett. Parts of the modern state were known previously as Livonia (from Estonian liiv "sand") and Courland (from Curonians, the name of a Lettish people, which is of unknown origin). Related: Latvian.
laud (v.): "praise highly, sing the praises of," late 14c., from Old French lauder "to praise, extol," from Latin laudare "to praise, commend, honor, extol, eulogize," from laus (genitive laudis) "praise, fame, glory." Probably from an echoic PIE root *leu- and cognate with Old English leoð "song, poem, hymn," from Proto-Germanic *leuthan (source also of Old Norse ljoð "strophe," German Lied "song," Gothic liuþon "to praise"). Related: Lauded; lauding.
laudable (adj.): early 15c., from Old French laudable "praiseworthy, glorious" and directly from Latin laudabilis "praiseworthy," from laudare "to praise, commend, extol" (see laud). Related: Laudably.
laudanum (n.): c. 1600, from Modern Latin laudanum (1540s), coined by Paracelsus for a medicine he mixed, supposed to contain gold and crushed pearls and many expensive ingredients, but probably owing its effectiveness to only one of them, opium. Perhaps from Latin laudare "to praise" (see laud), or from Latin ladanum "a gum resin," from Greek ladanon, a word perhaps of Semitic origin. The word soon came to be used for "any alcoholic tincture of opium." Latin ladanum was used in Middle English of plant resins, but this is not regarded as the source of the 16c. word.
laudation (n.): "act of praising, commendation," late 15c., from Latin laudationem (nominative laudatio) "a praising, commendation," noun of action from past participle stem of laudare "to praise" (see laud).
laudator temporis acti: Latin phrase used of one who looks to the past as better times, 1736, from Horace's laudator temporis acti se puero "a praiser of times past when he was a boy" [Ars Poetica, 173], from laudator, agent noun of laudare "to praise" (see laud).
laudatory (adj.): "expressing praise," 1550s, from Middle French laudatoire and directly from Late Latin laudatorius, from Latin laudare "to praise" (see laud).
lauds (n.): "morning Church service in which psalms of praise to God (Psalms 148-150) are sung," mid-14c., from Old French Laudes "sung devotions; Lauds;" see laud.
laugh (v.): late 14c., from Old English (Anglian) hlæhhan, earlier hliehhan, hlihhan "to laugh, laugh at; rejoice; deride," from Proto-Germanic *klakhjan (source also of Old Norse hlæja, Danish le, Old Frisian hlakkia, Old Saxon hlahhian, Middle Dutch and Dutch lachen, Old High German hlahhan, German lachen, Gothic hlahjan), from PIE *kleg-, of imitative origin (compare Latin cachinnare "to laugh aloud," Sanskrit kakhati "laughs," Old Church Slavonic chochotati "laugh," Lithuanian klageti "to cackle," Greek kakhazein).

Originally with a "hard" -gh- sound, as in Scottish loch; the spelling remained after the pronunciation shifted to "-f." To laugh in one's sleeve is to laugh inwardly so as not to be observed:
If I coveted nowe to avenge the injuries that you have done me, I myght laughe in my slyve. [John Daus, "Sleidanes Commentaries," 1560]
"The phrase generally implies some degree of contempt, and is used rather of a state of feeling than of actual laughter" [Century Dictionary]. Related: Laughed; laugher; laughing.
laugh (n.): 1680s, "action of laughing," from laugh (v.). The older noun form is laughter. Meaning "a cause of laughter" is from 1895; ironic use (in that's a laugh) attested from 1930. Laugh track "pre-recorded laughter on a TV program" is from 1961.
laughable (adj.): "fitted to excite laughter," 1590s, from laugh (v.) + -able. Related: Laughably. In this sense Old English had hleaterlic "laughterly."
laughing (n.): mid-14c., verbal noun from laugh (v.). Laughing matter (usually with negative) is from 1560s. Nitrous oxide has been called laughing gas since 1842 (for its exhilarating effects). Davy, experimenting with the gas, discovered these as far back as 1779: "When I took the bag from my mouth, I immediately laughed. The laughter was involuntary, but highly pleasurable, accompanied by a thrill all through me."
laughing-stock (n.): also laughingstock; 1510s, formed by analogy with whipping-stock "whipping post," later also "object of frequent whipping" (but that word is not attested in writing in this sense until 1670s). See laughing + stock (n.1). Also in the same sense was jesting-stock (1530s), and compare gaping-stock "person or thing regarded as an object of wonder." A Latin word for it was irridiculum.
Laughlin: Gaelic Lachlann, earlier Lochlann, literally "lake-" or "fjord-land," i.e. "Scandinavia;" as a name, denoting "one from Norway."
laughter (n.): late 14c., from Old English hleahtor "laughter; jubilation; derision," from Proto-Germanic *hlahtraz (source also of Old Norse hlatr, Danish latter, Old High German lahtar, German Gelächter); see laugh (v.).
launch (v.): c. 1300, "to rush, plunge, leap, start forth; to be set into sudden motion," from Old North French lancher, Old French lancier "to fling, hurl, throw, cast," from Late Latin lanceare "wield a lance," from Latin lancea "light spear" (see lance (n.)).

Meaning "to throw, hurl, let fly" is from mid-14c. Sense of "set (a boat) afloat" first recorded c. 1400, from notion of throwing it out on the water; generalized by 1600 to any sort of beginning. Related: Launched; launching.
launch (n.2): "large boat carried on a warship," 1690s, from Portuguese lancha "barge, launch," apparently from Malay lancharan, from lanchar "quick, agile;" if so, the English spelling has been influenced by launch (v.).
launch (n.1): "a leap or a bound," mid-15c., from launch (v.). Meaning "place where a boat is launched" is from 1711. Meaning "the liftoff of a missile, spacecraft, etc." is from 1935. Launch pad attested from 1960.
launder (v.): 1660s, "to wash linen," from noun launder "one who washes" (especially linen), mid-15c., a contraction of lavender, from Old French lavandier "washer, launderer" (12c.), from Medieval Latin lavandaria "a washer," which is ultimately from Latin lavare "to wash" (see lave). Criminal banking sense first recorded 1961, from notion of making dirty money clean; the word in this sense was brought to widespread use during U.S. Watergate scandal, 1973. Related: Laundered; laundering.
launderer (n.): mid-15c., lawnderer "washerwoman, laundress;" see launder + -er (1).
laundress (n.): 1540s; see laundry + -ess.
laundromat (n.): "automatic coin-operated public laundry," 1946, originally (1942) a proprietary name by Westinghouse for a type of automatic washing machine; from laundry + ending probably suggested by automat. Earlier words for public clothes-washing places in U.S. were washateria (1935), laundrette (1945). Launderette is from 1947. The Westinghouse machine was popular after World War II and was available with coin chutes and timers.
laundry (n.): late 14c., "place for washing;" mid-15c., "act of washing," a contraction (compare launder) of Middle English lavendrie (late 13c.), from Old French lavanderie "wash-house," from Vulgar Latin lavandaria "things to be washed," plural of lavandarium, from lavare "to wash" (see lave). English meaning "articles that need to be or have been laundered" is from 1916. As a verb, from 1880. Laundry list in figurative sense is from 1958.
Laura: fem. proper name, from Italian, probably originally a pet form of Laurentia, fem. of Laurentius (see Laurence). Among the top 20 names for girls born in U.S. between 1963 and 1979.
Laurasia: Paleozoic supercontinent comprising North America and Eurasia, 1931, from German (1928), from Laurentia, geologists' name for the ancient core of North America (see Laurentian) + second element of Eurasia.
laureate (adj.): "crowned with laurels" (as a mark of distinction), late 14c., earliest reference is to poetic distinction, from Latin laureatus "crowned with laurels," from laurea "laurel crown" (emblematic of victory or distinction in poetry), from fem. of laureus "of laurel," from laurus "laurel" (see laurel (n.)).

Laureat poete is first found in "Canterbury Tales" (in reference to Petrarch -- Fraunceys Petrak); it also was used in Middle English of Aesop and, by early 15c., of Chaucer. Inverted form poet laureate, in imitation of Latin word order, is from c. 1400 in English); the first official one probably was Ben Jonson (1638), though the first recorded one was Dryden (1668). Extended 1947 to Nobel prize winners. As a noun, 1520s, from the adjective or from a mistaken reading of poet laureate. Related: Laureateship (1732), laureation.
laurel (n.): mid-14c. variant of lorrer (c. 1300), from Old French laurier, lorier "bay tree, laurel tree" (12c.), from Latin laurus "laurel tree," which is probably related to Greek daphne "laurel" (for change of d- to l- see lachrymose), which is probably from a pre-IE Mediterranean language.

The second -r- changed to -l- in late Middle English by dissimilation. An emblem of victory or of distinction, hence the phrase to rest (originally repose) on one's laurels, first attested 1831. Related: Laurine (adj.).
Laurence: masc. proper name, from Old French Lorenz (French Laurent), from Latin Laurentius, literally "of Laurentum," a maritime town in Latium, the name of which means literally "town of bay trees," from laurus (see laurel). The Italian form is Lorenzo.

A popular given name in the Middle Ages, as a surname it is attested in England from mid-12c. Larkin is a pet-form, along with Larry. For some reason, the name since at least 18c. has been the personification of indolence (compare German der faule Lenz "Lazy Lawrence"). But in Scotland, the pet form Lowrie has been used for "a fox" (c. 1500), also for "a crafty person" (1560s). Lawrence is the Law- in the surname LawsonLowery/Laurie, etc.
Laurentian: in reference to granite strata in eastern Canada, 1854 (Sir W.E. Logan and T. Sterry Hunt), named for the Laurentian Mountains (where it is found), which are named for the nearby St. Lawrence River (see Laurence). Hence, Laurasia. The Laurentian library in Florence is named for Lorenzo (Latin Laurentius) de' Medici.
lautitious (adj.): "sumptuous," 1640s, from Latin lautitia "elegance, splendor, magnificence," from lautus "neat, elegant, splendid," literally "washed," past participle of lavare "to wash" (see lave).
lav (n.): 1913 as a colloquial shortening of lavatory.
lava (n.): "molten rock issuing from a volcano," 1750, from Italian (Neapolitan or Calabrian dialect) lava "torrent, stream," traditionally said to be from Latin lavare "to wash" (see lave). Originally applied in Italian to flash flood rivulets after downpours, then to streams of molten rock from Vesuvius. Alternative etymology is from Latin labes "a fall," from labi "to fall, slip" (see lapse (n.)). As an adjective, lavatic (1805), laval (1883). Lava lamp is attested from 1965, also lava light (reg. U.S., 1968, as Lava Lite).
lavage (n.): "a washing," 1884, from French lavage, from laver "to wash," from Latin lavare "to wash" (see lave).
lavalier (n.): kind of ornament that hangs around the neck, 1873, from French lavallière, a kind of tie, after Louise Françoise de La Baume Le Blanc de La Vallière, Duchesse de La Vallière (1644-1710), mistress of Louis XIV from 1661-1667.
lavaliere: see lavalier.
lavation (n.): "act of washing, a cleansing," 1620s, from Latin lavationem (nominative lavatio) "a bathing, bath, bathing apparatus," noun of action from past participle stem of lavare "to wash" (see lave). Related: Lavations.
lavatory (n.): late 14c., "washbasin," from Late Latin lavatorium "place for washing," noun use of neuter of Latin adjective lavatorius "pertaining to washing," from lavat-, past participle stem of lavare "to wash," from PIE root *leu(e)- (see lave). Sense of "washroom" is first attested 1650s; as a euphemism for "toilet, W.C.," it is attested by 1864. Related: Lavatorial.
lave (v.): c. 1200 (transitive), from Old English lafian "wash by pouring water on, pour (water)," possibly an early Anglo-Saxon or West Germanic borrowing (compare Dutch laven, German laben) of Latin lavare "to wash," or its Old French descendant, laver, or some confusion in English of the two. Latin lavare is from the PIE root *leu(e)- "to wash" (source also of Latin luere "to wash," Greek louein "to wash, bathe," Old Irish loathar "basin," Breton laouer "trough," Old English leaþor "lather," læg "lye").
lavender (n.): "fragrant plant of the mint family," c. 1300, from Anglo-French lavendre, Old French lavendre "the lavender plant," from Medieval Latin lavendula "lavender" (10c.), perhaps from Latin lividus "bluish, livid." If so, it probably was associated with French lavande, Italian lavanda "a washing" (from Latin lavare "to wash;" see lave) because it was used to scent washed fabrics and as a bath perfume.

The adjective meaning "of a pale purple color, of the color of lavender flowers" is from 1840; as a noun in the color sense from 1882. An identical Middle English word meant "laundress, washerwoman;" also, apparently, "prostitute, whore; camp follower" and is attested as a surname from early 13c.
lavish (adj.): "spending or bestowing profusely," mid-15c., from Middle French lavasse (n.) "torrent of rain, deluge" (15c.), from Old French lavache, from laver "to wash," from Latin lavare "to wash" (see lave). Related: Lavishly; lavishness.