Online Etymology Dictionary

lassitude (n.): early 15c., from Latin lassitudinem (nominative lassitudo) "faintness, weariness," from lassus "faint, tired, weary," from PIE *led-to-, suffixed form of *led- "slow, weary" (source also of Old English læt "sluggish, slow;" see late (adj.)), from root *le- (2) "to let go, slacken" (see lenient).
lasso (n.): "long rope with a running noose," used for catching horses and cattle, 1808, earlier laço (1768), American English, from Spanish lazo "a snare, slipknot," from Latin laqueum (nominative laqueus) "noose, snare" (see lace (n.)). As a verb from 1807. Related: Lassoed; lassoing. A lasso can serve as a lariat, but the reverse is not true.
last (v.): "endure, go on existing," from Old English læstan "to continue, endure," earlier "follow (a leader), accomplish, carry out, perform," from Proto-Germanic *laistjan "to follow a track" (source also of Gothic laistjan "to follow after," Old Frisian lasta "to fulfill, to pay (duties)," German leisten "to perform, achieve, afford"), from PIE *leis- (1) "track, furrow" (see learn). Related to last (n.1), not to last (adj.). Related: Lasted; lasting.
last (n.1): "wooden model of a human foot used by shoemakers," from Old English læste "shoemaker's last," earlier last "track, footprint, footstep, trace," from Proto-Germanic *laist- (source also of Old Norse leistr "the foot," Middle Dutch, Dutch leest "form, model, last," Old High German leist "track, footprint," German Leisten "last," Gothic laistjan "to follow," Old English læran "to teach"), from PIE root *leis- (1) "track, furrow" (see learn). Related to last (v.).
last (n.2): late Old English, "the last or final man, object, time, etc.," from last (adj.). From late 14c. as "most recent person, latest comer." Also in Middle English as a noun, "duration" (early 14c.), from the verb. Phrase at (the) last is from c. 1200; extended form long last is from 1520s. To the last is from c. 1400.
last (adv.): c. 1200, "most recently;" early 13c., "finally, after all others" (contrasted to first), contraction of Old English lætest (adv.), superlative of late (see late).
last (adj.): c. 1200, "latest, final, following all others," a contraction of Old English latost (adj.) "slowest, latest," superlative of læt (see late); in some uses from late (adv.). Cognate with Old Frisian lest, Dutch laatst, Old High German laggost, German letzt.

Meaning "last in space, furthest, most remote" is from late 14c.; meaning "most unlikely or unsuitable" is from mid-15c. Meaning "most recent, next before the present" (as in last night, last September) is from late 14c.; latest would be more correct, but idiom rules and the last time I saw her might mean the most recent time this hour or the final time forever.

The biblical last days ("belonging to the end") is attested from late 14c. Last hurrah is from the title of Edwin O'Connor's 1956 novel. Last word "final, definitive statement" is from 1650s. A dying person's last words so called by 1740. As an adjective, last-minute attested from 1913. Last-chance (adj.) is from 1962. Expression if it's the last thing I do, expressing strong determination, is attested by 1905.
last-ditch (adj.): "on the last line of defense," 1909, from an image attested by 1715, from a quote attributed to William of Orange (1650-1702), who is said to have uttered it defiantly during the French invasion of 1672; if so, originally in a Netherlands context.
We have no space to enter into the detail of the heroic struggle maintained by the young stadtholder and his faithful Dutchmen; how they laid their country under water, and successfully kept the powerful invader at bay. Once the contest seemed utterly hopeless. William was advised to compromise the matter, and yield up Holland as the conquest of Louis XIV. "No," replied he; "I mean to die in the last ditch." A speech alone sufficient to render his memory immortal. [Agnes Strickland, "Lives of the Queens of England," London, 1847]
lasting (adj.): "continuing in time," late Old English, present participle adjective from last (v.). Related: Lastingly; lastingness.
lastly (adv.): late 14c., from last (adj.) + -ly (2).
latakia (n.): type of fine Turkish tobacco, 1833, from Latakia, city in Syria (see Laodicean).
latch (v.): Old English læccan "to grasp or seize, catch hold of," also "comprehend," from Proto-Germanic *lakkijanan. Not found in other Germanic languages; according to Watkins probably from PIE *(s)lagw- "to seize" (see analemma). In its original sense the verb was paralleled and then replaced by French import catch (v.). Meaning "to fasten with a latch" is mid-15c. Related: Latched; latching.
latch (n.): "device for catching and retaining," especially "a fastening for a door," late 13c., probably from latch (v.).
latch-key (n.): also latchkey, "a key to raise or draw back the latch of a door" and allow one to enter from outside, 1825, from latch (n.) + key (n.1). Latchkey child first recorded 1944, American English, in reference to children coming home from school while both parents are away at work.
Many elementary school principals and teachers have always known the "latchkey" child or the "eight-hour orphan." [New York State Teachers Association, "New York State Education," 1944]
The older or simpler device was a latch-string, which could be pulled in to lock up; having it out was symbolic of openness.
latchet (n.): "strap or thong of a sandal or shoe," late 14c., lachet, from Old French lachet, variant of lacet, diminutive of las, laz "noose, string, cord, tie" (see lace (n.)). Spelling altered perhaps by influence of latch.
late (adj.): Old English læt "occurring after the customary or expected time," originally "slow, sluggish, slack, lax, negligent," from Proto-Germanic *lata- (source also of Old Norse latr "sluggish, lazy," Middle Dutch, Old Saxon lat, Dutch laat, German laß "idle, weary," Gothic lats "weary, sluggish, lazy," latjan "to hinder"), from PIE *led- "slow, weary" (source also of Latin lassus "faint, weary, languid, exhausted," Greek ledein "to be weary"), from root *le- (2) "to let go, slacken" (see let (v.)); and compare let (n.).

From mid-13c. as "occurring in the latter part of a period of time." From c. 1400 as "being or occurring in the near, or not too distant, past; recent" (of late). From this comes the early 15c. sense "recently dead, not many years dead" (as in the late Mrs. Smith). Of menstruation, attested colloquially from 1962. Expression better late than never is attested from late 15c. As an adverb, from Old English late "slowly."
latebrous (adj.): "full of hiding places," 1650s, from Latin latebrosus, from latebra "a hiding place," from latere "to lie hidden" (see latent). Hence latebricole "living or lurking in holes" (of spiders, etc.), from Latin latebricola "one who dwells in lurking places."
lateen: 1727, nativized spelling of French latine in voile latine, literally "Latin sail;" see Latin (adj.). So called because it was used in the Mediterranean.
lately (adv.): Old English lætlice "slowly, sluggishly;" see late (adj.) + -ly (2). Meaning "within recent times, not long ago" is from late 15c., probably a new formation.
latency (n.): 1630s, "condition of being concealed, unobserved existence," from latent + -cy. Meaning "delay between stimulus and response" is from 1882 (perhaps via the notion of "dormancy"); computer sense (latency time) is from 1954.
lateness (n.): Old English lætness "slowness," from late (adj.) + -ness. From late 14c. as "a being advanced in time;" from 1881 as "a being behind the proper time."
latent (adj.): mid-15c., "concealed, secret," from Latin latentem (nominative latens) "lying hid, concealed, secret, unknown," present participle of latere "lie hidden, lurk, be concealed," from PIE *late-, suffixed form of root *lādh- "to be hidden" (source also of Greek lethe "forgetfulness, oblivion," lethargos "forgetful," lathre "secretly, by stealth," lathrios "stealthy," lanthanein "to be hidden;" Old Church Slavonic lajati "to lie in wait for"). Meaning "dormant, undeveloped" is from 1680s, originally in medicine.
later (adj., adv.): "afterward," 16c., comparative of late. A modern formation; the Old English comparative lator developed into latter. As a salutation, "farewell," from 1954, U.S. colloquial, short for adverbial use in (I'll) see you later.
lateral (adj.): "of or pertaining to the side," early 15c., from Olde French latéral (14c.) and directly from Latin lateralis "belonging to the side," from latus (genitive lateris) "the side, flank; lateral surface" (see oblate (n.)). Specific sense "situated on either side of the median vertical longitudinal plane of the body" [Century Dictionary] is from 1722. As a noun, from 1630s, "a side part;" as a type of pass to the side in U.S. football, it is attested from 1934 (short for lateral pass). Related: Laterally.
laterality (n.): 1640s; see lateral + -ity.
Lateran: c. 1300, popular name of the cathedral church of St. John Lateran at Rome, which is built on the site of the palace of the Plautii Laterani, a Roman family. Given by Constantine to the bishop of Rome, as a papal headquarters and residence for nearly 1,000 years it was the site of five general councils of the Western Church, that of 1215 being regarded as most important. The Lateran Accords of 1929 settled the relationship between Italy and the Holy See.
latero-: comb. form used from 19c. to represent Latin latus "side" (see oblate (n.)).
latescent (adj.): "tending to become latent or obscure, not obvious to perception," 1836, from Latin latescentem (nominative latescens), present participle of latescere "to hide oneself, be hidden," inchoative of latere "to lie hidden" (see latent). Related: Latescence.
latesome (adj.): Old English lætsum "backward, slow, sluggish;" see late + -some (1).
latest (adj.): c. 1200, "last, final," superlative of late. From 1590s as "most recent." As a noun, 1520s, "the last in order." Colloquial the latest "the news" attested from 1886. At the latest "at the most distant date" is from 1884.
latex (n.): 1660s, "body fluid," from Latin latex (genitive laticis) "liquid, a liquid, fluid," probably from Greek latax "dregs," from PIE root *lat- "wet, moist" (source also of Middle Irish laith "beer," Welsh llaid "mud, mire," Lithuanian latakas "pool, puddle," Old Norse leþja "filth").

From 1835 as "milky liquid from plants." Meaning "water-dispersed polymer particles" (used in rubber goods, paints, etc.) is from 1937. As an adjective by 1954, in place of the classically correct laticiferous.
lath (n.): "thin strip of wood" used chiefly in roof-building and plastering, late 13c., probably from an unrecorded Old English *læððe, variant of lætt "beam, lath," which is apparently from a Proto-Germanic *laþþo (source also of Old Saxon, Old Norse latta, Middle Dutch, German latte "lath," Dutch lat, Middle High German lade "plank," which is the source of German Laden "counter," hence, "shop"), but there are phonetic difficulties.
lath (v.): "to cover or line with laths," 1530s, from lath (n.). Related: Lathed; lathing.
lathe (n.): "machine for turning wood, etc., so it can be worked by a tool held at rest," early 14c., of uncertain origin, probably from a Scandinavian source. OED compares Danish drejelad "turning-lathe;" other compounds with the element suggest a sense "framework, supporting structure." Others see a possible connection to Old Norse hloeða "to lade, load, saddle (a horse)."
lather (n.): Old English leaþr "foam, soap, washing soda," from Proto-Germanic *lauthran (source also of Old Norse lauðr "washing soap, foam"), from PIE *loutro- (source also of Gaulish lautron, Old Irish loathar "bathing tub," Greek louein "to bathe," Latin lavere "to wash"), which is from root *leu(e)- "to wash" (see lave (v.)) + instrumentative suffix *-tro-.

The modern noun might be a 16c. redevelopment from the verb. Meaning "violent perspiration" (especially of horses) is from 1650s; hence the transferred sense "state of agitation" (such as induces sweating), attested from 1839.
lather (v.): from a Middle English variant of letheren (v.), from Old English leþran (late West Saxon lyþran) "become covered with (sweat, blood, etc.)," also transitive, from Proto-Germanic *lauthrjan (source also of Old Norse leyðra "to clean, wash;" see lather (n.)). Meaning "to form in froth, produce suds or foam" is from c. 1600. Related: Lathered; lathering.
Latian (adj.): 1590s, "of or pertaining to Latium (see Latin).
Latimer: also Lattimore, etc., surname, c. 1200, from late Old English latimer "interpreter," from Old French latimier, corruption of latinier, from Latin latinarius "interpreter," literally "a speaker of Latin" (see Latin (n.)). The corruption was perhaps originally graphic (OED) or arose in Vulgar Latin.
Latin (n.): "the language of the (ancient) Romans," Old English latin "Latin, the language of the Romans; any foreign language," from Latin latinium "the Latin language," noun use of the adjective latinius (see Latin (adj.)). The more common form in Old English was læden, from Vulgar Latin *ladinum, which probably was deformed by influence of Old English leoden "language." For "the Latin language" Old English also had lædenspræc.

In Old French the word was used very broadly, "speech, language:" "What Latin was to the learned, that their tongue was to laymen; hence latino was used for any dialect, even Arabic and the language of birds ...." [Donkin, "Etymological Dictionary of the Romance Languages," 1864].

Roughly speaking, Old Latin is the Latin before the classical period including early authors and inscriptions. Classical Latin flourished from about 75 B.C.E. to about 200 C.E., the Latin of Lucretius, Catullus, Caesar, Cicero, Virgil, Horace, Ovid, Livy, Seneca, etc.; it is the standard Latin of the grammars and dictionaries. Late Latin followed the classical period to about 600 and includes the early church fathers. Medieval Latin was the Latin of the Middle Ages, from about 600 to 1500. Modern Latin is Latin as written from about 1500 on, largely by scientific writers in description and classification. Vulgar Latin was the speech of the Roman home and marketplace, going on concurrently under Classical and Late Latin.
Latin (adj.): Old English latin "in Latin," from Latin Latinus "Latin, Roman, in Latin," literally "belonging to Latium," the region of Italy around Rome, a name of uncertain origin. Possibly from PIE root *stela- "to spread, extend," with a sense of "flat country" (as opposed to the mountainous district of the Sabines), or from a prehistoric non-IE language. Old folk etymology connected it with Latin latere "to lie hidden," and a fable of Saturn.

The Latin word also is the source of Spanish and Italian ladino, Dutch latijn, German latein, Irish Gaelic laidionn (n.), Polish lacina, Russian latuinŭ. The more common form in Old English was læden (see Latin (n.)).

In reference to the Roman Catholic Church, 1550s. Used as a designation for "people whose languages descend from Latin" (1856), hence Latin America (1862). The Latin Quarter (French Quartier latin) of Paris, on the south (left) bank of the Seine, was the site of university buildings in the Middle Ages, hence it was the place where Latin was spoken. The surname Latimer means "interpreter," literally "a speaker of Latin."
Latin America: 1862; see Latin (adj.). The notion is the nations whose languages descend from Latin. Related: Latin American (adj.), 1871.
Latinate (adj.): "derived from or characteristic of Latin," 1858, from Latin (n.) + -ate (1). An earlier adjective was Latinesque (1864). Wyclif (1388) has Latinly and Old English had lædenisc, lædenlic.
Latinism (n.): "a Latin idiom or expression," 1560s, from Latin (n.) + -ism.
Latinist (n.): "a student of Latin, an expert in Latin," 1530s, from Latin (n.) + -ist. Also Latiner (1690s), and, for the petty sort, Latinitaster (1836).
Latinity (n.): 1610s, "pure Latin style," from Latin latinitas, from Latinus (see Latin (adj.)). From 1880 as "the civil rights of ancient Latins."
Latinize (v.): "to render like or into the Latin language," 1580s, from Latin (n.) + -ize. Related: Latinized; Latinizing. The earlier verb was simply latin (1560s).
Latino: "male Latin-American inhabitant of the United States" (fem. Latina), 1946, American English, from American Spanish, a shortening of Latinoamericano "Latin-American" (see Latin America). As an adjective, attested from 1974.
Latino-: prefix in use from 1939 as a comb. form of Latin, from ablative of Latin latinus. By 1958 as a comb. form from Latino.
latitude (n.): late 14c., "breadth," from Old French latitude (13c.) and directly from Latin latitudo "breadth, width, extent, size," from latus "wide, broad, extensive," from Old Latin stlatus, from PIE *stleto-, suffixed form of root *stele- "to spread, to extend" (source also of Old Church Slavonic steljo "to spread out," Armenian lain "broad"). Geographical and astronomical senses also are from late 14c., literally "breadth" of a map of the known world. Figurative sense of "allowable degree of variation, extent of deviation from a standard" is early 15c. Related: Latitudinal "pertaining to geographic latitude" (1777); latitudinous "having broadness of interpretation" (1829, American English).
latitudinarian (adj.): 1660s, "characterized by broad-mindedness," especially in reference to 17c. Episcopal clergymen indifferent to doctrinal details; a pseudo-Latin construction from latitude in its meaning "freedom from narrow restrictions" (c. 1600) + ending as in sectarian, etc. Also as a noun from 1660s. Related: Latitudinarianism "liberality of opinion in religion" (1670s); earlier in that sense was latitudinism (1660s).