leakage (n.) Look up leakage at Dictionary.com
late 15c., from leak (v.) + -age.
leaky (adj.) Look up leaky at Dictionary.com
mid-15c., from leak (n.) + -y (2). Related: Leakiness.
leal (adj.) Look up leal at Dictionary.com
"loyal, faithful, honest, true," c.1300, lele, surviving from Middle English as Northern English and Scottish form of loyal. The Land of the leal is Heaven, not Scotland.
lean (v.) Look up lean at Dictionary.com
c.1200, from Old English hleonian "to bend, recline, lie down, rest," from Proto-Germanic *khlinen (cognates: Old Saxon hlinon, Old Frisian lena, Middle Dutch lenen, Dutch leunen, Old High German hlinen, German lehnen "to lean"), from PIE root *klei- "to lean, to incline" (cognates: Sanskrit srayati "leans," sritah "leaning;" Old Persian cay "to lean;" Lithuanian slyti "to slope," slieti "to lean;" Latin clinare "to lean, bend," clivus "declivity," inclinare "cause to bend," declinare "bend down, turn aside;" Greek klinein "to cause to slope, slant, incline;" Old Irish cloin "crooked, wrong;" Middle Irish cle, Welsh cledd "left," literally "slanting;" Welsh go-gledd "north," literally "left" -- for similar sense evolution, see Yemen, Benjamin, southpaw).

Meaning "to incline the body against something for support" is mid-13c. Figurative sense of "to trust for support" is from early 13c. Sense of "to lean toward mentally, to favor" is from late 14c. Related: Leaned; leaning. Colloquial lean on "put pressure on" (someone) is first recorded 1960.
lean (adj.) Look up lean at Dictionary.com
"thin, spare, with little flesh or fat," c.1200, from Old English hlæne "lean, thin," possibly from hlænan "cause to lean or bend," from Proto-Germanic *khlainijan, which would connect it to Old English hleonian (see lean (v.)). But perhaps rather, according to OED, from a PIE *qloinio- (with cognates in Lithuanian klynas "scrap, fragment," Lettish kleins "feeble"). Extended and figurative senses from early 14c. The noun meaning "lean animals or persons" is from c.1200, from the adjective.
lean (n.) Look up lean at Dictionary.com
"action or state of leaning," 1776, from lean (v.).
lean-to (n.) Look up lean-to at Dictionary.com
"building whose rafters pitch against another building or wall," mid-15c., from lean (v.) + to.
Leander Look up Leander at Dictionary.com
youth of Abydos, lover of Hero, who swam nightly across the Hellespont to visit her, from Greek Leiandros, literally "lion-man," from leon "lion" + aner (genitive andros) "man" (see anthropo-).
leanness (n.) Look up leanness at Dictionary.com
Old English hlænnesse; see lean (adj.) + -ness.
leap (v.) Look up leap at Dictionary.com
c.1200, from Old English hleapan "to jump, run, leap" (class VII strong verb; past tense hleop, past participle hleapen), from Proto-Germanic *hlaupan (cognates: Old Saxon hlopan, Old Norse hlaupa, Old Frisian hlapa, Dutch lopen, Old High German hlouffan, German laufen "to run," Gothic us-hlaupan "to jump up"), of uncertain origin, with no known cognates beyond Germanic. Leap-frog, the children's game, is attested by that name from 1590s; figurative use by 1704.
First loke and aftirward lepe [proverb recorded from mid-15c.]
Related: Leaped; leaping.
leap (n.) Look up leap at Dictionary.com
c.1200, from Old English hliep, hlyp (West Saxon), *hlep (Mercian, Northumbrian) "a leap, bound, spring, sudden movement; thing to leap from;" common Germanic (cognates: Old Frisian hlep, Dutch loop, Old High German hlouf, German lauf); from the root of leap (v.). Leaps has been paired with bounds since at least 1720.
leap year (n.) Look up leap year at Dictionary.com
late 14c., from leap (v.) + year. So called from its causing fixed festival days, which normally advance one weekday per year, to "leap" ahead one day in the week.
learn (v.) Look up learn at Dictionary.com
Old English leornian "to get knowledge, be cultivated, study, read, think about," from Proto-Germanic *liznojan (cognates: Old Frisian lernia, Middle Dutch leeren, Dutch leren, Old High German lernen, German lernen "to learn," Gothic lais "I know"), with a base sense of "to follow or find the track," from PIE *leis- (1) "track, furrow." Related to German Gleis "track," and to Old English læst "sole of the foot" (see last (n.)).

The transitive sense (He learned me how to read), now vulgar, was acceptable from c.1200 until early 19c., from Old English læran "to teach" (cognates: Dutch leren, German lehren "to teach," literally "to make known;" see lore), and is preserved in past participle adjective learned "having knowledge gained by study." Related: Learning.
learnable (adj.) Look up learnable at Dictionary.com
1620s, from learn + -able.
learned (adj.) Look up learned at Dictionary.com
"having knowledge gained by study," mid-14c., past participle adjective from learn (v.) in former transitive sense. Related: Learnedly; learnedness.
learning (n.) Look up learning at Dictionary.com
Old English leornung "learning, study," from leornian (see learn). Learning curve attested by 1907.
lease (n.) Look up lease at Dictionary.com
late 14c., "legal contract conveying property, usually for a fixed period of time and with a fixed compensation," from Anglo-French les (late 13c.), from lesser "to let, let go," from Old French laissier "to let, allow, permit; bequeath, leave," from Latin laxare "loosen, open, make wide," from laxus "loose" (see lax). Modern French equivalent legs is altered by erroneous derivation from Latin legatum "bequest, legacy."
lease (v.) Look up lease at Dictionary.com
late 15c., "to take a lease," from Anglo-French lesser, Old French laissier "to let, leave" (see lease (n.). Related: Leased; leasing. Lessor, lessee in contract language preserves the Anglo-French form.
leash (v.) Look up leash at Dictionary.com
"to attach to or with a leash," 1590s, from leash (n.). Related: Leashed; leashing.
leash (n.) Look up leash at Dictionary.com
"thong for holding a dog or hound," c.1300, from Old French laisse "hound's leash," from laissier "loosen," from Latin laxare, from laxus "loose" (see lax). Figurative sense attested from early 15c. The meaning "a set of three" is from early 14c., originally in sporting language.
least (adj.) Look up least at Dictionary.com
Old English læst, earlier læsest "smallest" (superlative of lytel "small"), from Proto-Germanic superlative *laisistaz (see less). Qualifying phrase at least is Middle English æt læstan. As a noun, from early 12c.; as an adverb, c.1200.
leastways Look up leastways at Dictionary.com
1825, colloquial, from least + way (n.). Regarded as vulgar, but simply a one-word form of Chaucer's leest weye (late 14c.).
leather (n.) Look up leather at Dictionary.com
Old English leðer (in compounds only) "hide, skin, leather," from Proto-Germanic *lethran (cognates: Old Norse leðr, Old Frisian lether, Old Saxon lethar, Middle Dutch, Dutch leder, Old High German ledar, German leder), from PIE *letro- "leather" (cognates: Old Irish lethar, Welsh lledr, Breton lezr). As an adjective from early 14c.; it acquired a secondary sense of "sado-masochistic" 1980s, having achieved that status in homosexual jargon in the 1970s.
leathern (adj.) Look up leathern at Dictionary.com
Old English leðren; see leather + -en (2).
leatherneck (n.) Look up leatherneck at Dictionary.com
"U.S. Marine," 1914, Navy slang, from leather + neck (n.). So called for the leather collars of their early uniforms; earlier in British use (1890) as a sailor's term for a soldier.
leathery (adj.) Look up leathery at Dictionary.com
1550s, from leather + -y (2). Related: Leatheriness.
leave (v.) Look up leave at Dictionary.com
Old English læfan "to let remain; remain; have left; bequeath," from Proto-Germanic *laibijan (cognates: Old Frisian leva "to leave," Old Saxon farlebid "left over"), causative of *liban "remain," (source of Old English belifan, German bleiben, Gothic bileiban "to remain"), from root *laf- "remnant, what remains," from PIE *leip- "to stick, adhere;" also "fat."

The Germanic root has only the sense "remain, continue," which also is in Greek lipares "persevering, importunate." But this usually is regarded as a development from the primary PIE sense of "adhere, be sticky" (compare Lithuanian lipti, Old Church Slavonic lipet "to adhere," Greek lipos "grease," Sanskrit rip-/lip- "to smear, adhere to." Seemingly contradictory meaning of "depart" (early 13c.) comes from notion of "to leave behind" (as in to leave the earth "to die;" to leave the field "retreat").
leave (n.) Look up leave at Dictionary.com
"permission," Old English leafe "leave, permission, license," dative and accusative of leaf "permission," from Proto-Germanic *lauba (cognates: Old Norse leyfi "permission," Old Saxon orlof, Old Frisian orlof, German Urlaub "leave of absence"), from PIE *leubh- "to care, desire, love, approve" (see love (n.)). Cognate with Old English lief "dear," the original idea being "approval resulting from pleasure." Compare love, believe. In military sense, it is attested from 1771.
leave-taking (n.) Look up leave-taking at Dictionary.com
late 14c., from leave (n.) + present participle of take (v.).
leaved (adj.) Look up leaved at Dictionary.com
"having leaves," past participle adjective from verb leave "to put forth leaves," mid-13c., from leaf (n.).
leaven (n.) Look up leaven at Dictionary.com
mid-14c., from Old French levain "leaven, sourdough" (12c.), from Latin levamen "alleviation, mitigation," but used in Vulgar Latin in its literal sense of "a means of lifting, something that raises," from levare "to raise" (see lever). Figurative use from late 14c.
leaven (v.) Look up leaven at Dictionary.com
c.1400, from leaven (n.). Related: Leavened; leavening.
Lebanese Look up Lebanese at Dictionary.com
1860, from Lebanon + -ese.
Lebanon Look up Lebanon at Dictionary.com
nation in w. Asia, from Semitic root l-b-n "white," probably in reference to snow-capped peaks, or possibly to chalk or limestone cliffs. The Greek name of the island Lemnos is of Phoenician origin and from the same root.
lebensraum (n.) Look up lebensraum at Dictionary.com
"territory needed for a nation's or people's natural development," 1905, from German genitive of leben "life" (see life) + raum "space" (see room (n.)).
lecanomancy (n.) Look up lecanomancy at Dictionary.com
"divination by inspection of water in a basin," c.1600, from Latinized form of Greek lekane "dish-pan" + -mancy.
lech (n.1) Look up lech at Dictionary.com
"Celtic monumental stone," 1768, from Welsh llech, cognate with Gaelic and Irish leac (see cromlech).
lech (n.2) Look up lech at Dictionary.com
"yen, strong desire" (especially sexual), 1796, variant of letch. Meaning "a lecher" is by 1943.
lecher (n.) Look up lecher at Dictionary.com
"man given to excessive sexual indulgence," late 12c., from Old French lecheor (Modern French lécheur) "one living a life of debauchery," especially "one given to sexual indulgence," literally "licker," agent noun from lechier "to lick, to live in debauchery or gluttony," from Frankish *likkon or some other Germanic source, from Proto-Germanic *likkojan "to lick" or some other Germanic source (see lick). The Old French feminine form was lechiere. Middle English, meanwhile, had lickestre "female who licks;" figuratively "a pleasure seeker," literally "lickster."
lecherous (adj.) Look up lecherous at Dictionary.com
c.1300, probably from lecher + -ous; or else from rare Old French lecheros. Related: Lecherously; lecherousness.
lechery (n.) Look up lechery at Dictionary.com
c.1200, from Old French lecherie "impertinence, deceit," from lecheor (see lecher).
The priests had excellent cause to forbid us lechery: this injunction, by reserving to them acquaintance with and absolution for these private sins, gave them an incredible ascendancy over women, and opened up to them a career of lubricity whose scope knew no limits. [Marquis de Sade, "Philosophy in the Bedroom"]
lecithin (n.) Look up lecithin at Dictionary.com
fatty substance found in the yolks of eggs (among other places), 1861, from French lécithine (coined 1850 by N.T. Gobley), from Greek lekithos "egg yolk," + chemical suffix -ine (2). Greek lekithos is of unknown origin.
lectern (n.) Look up lectern at Dictionary.com
early 14c., lettorne, lettron, from Old French letron, from Medieval Latin lectrinum, from Late Latin lectrum "lectern," from root of Latin legere "to read" (see lecture (n.)). Half-re-Latinized in English in 15c.
lectio difficilior Look up lectio difficilior at Dictionary.com
Latin, literally "harder reading," from phrase maxim difficilior lectio potior. In textual reconstruction (of the Bible, etc.) the idea that, of two alternative manuscript readings, the one whose meaning is less obvious is less likely to be a copyist's alteration, and therefore should be given precedence.
lection (n.) Look up lection at Dictionary.com
1530s, from Old French lection, from Latin lectionem (nominative lectio), noun of action from past participle stem of legere "to read" (see lecture (n.)).
lector (n.) Look up lector at Dictionary.com
late 14c., "reader, a cleric in one of the minor orders," from Late Latin lector "reader," agent noun from Latin legere "to read" (see lecture (n.)). Related: Lectorship.
lecture (n.) Look up lecture at Dictionary.com
late 14c., "action of reading, that which is read," from Medieval Latin lectura "a reading, lecture," from Latin lectus, past participle of legere "to read," originally "to gather, collect, pick out, choose" (compare election), from PIE *leg- "to pick together, gather, collect" (cognates: Greek legein "to say, tell, speak, declare," originally, in Homer, "to pick out, select, collect, enumerate;" lexis "speech, diction;" logos "word, speech, thought, account;" Latin lignum "wood, firewood," literally "that which is gathered").

To read is to "pick out words." Meaning "action of reading (a lesson) aloud" is from 1520s. That of "a discourse on a given subject before an audience for purposes of instruction" is from 1530s.
lecture (v.) Look up lecture at Dictionary.com
1580s, from lecture (n.). Meaning "to address severely and at length" is from 1706. Related: Lectured; lecturing.
lecturer (n.) Look up lecturer at Dictionary.com
1580s, agent noun from lecture (v.).
LED (n.) Look up LED at Dictionary.com
1968, initialism (acronym) from light-emitting diode.