Online Etymology Dictionary

levator (n.): 1610s in anatomy, "type of muscle that raises or elevates," from medical Latin levator (plural levatores) "a lifter," from Latin levatus, past participle of levare "to raise, lift up; make lighter" (see lever). Opposed to depressor.
levee (n.2): "morning assembly held by a prince or king" (originally upon rising from bed), 1670s, a spelling intended to represent the pronunciation of French lever "a raising," noun use of verb meaning "to raise" (see levee (n.1)), or else from a variant form of levée in French, which, however, "has not the meaning 'a reception'" [Century Dictionary]. By mid-18c. the word in English was used of assemblies or receptions held at any hour.
levee (n.1): 1719, "natural or artificial embankment to prevent overflow of a river," from New Orleans French levée "a raising, a lifting; an embankment," from French levée, literally "a rising" (as of the sun), noun use of fem. past participle of lever "to raise," from Latin levare "to raise, lift up; make lighter" (see lever). They also were used as landing places.
level (n.): mid-14c., "tool to indicate a horizontal line," from Old French livel "a level" (13c.), ultimately from Latin libella "a balance, level" (also a monetary unit), diminutive of libra "balance, scale, unit of weight" (see Libra). Spanish nivel, Modern French niveau are from the same source but altered by dissimilation.

Meaning "position as marked by a horizontal line" (as in sea-level) is from 1530s; meaning "flat surface" is from 1630s; meaning "level tract of land" is from 1620s. Figurative meaning in reference to social, moral, or intellectual condition is from c. 1600. Figurative phrase on the level "fair, honest" is from 1872; earlier it meant "moderate, without great ambition" (1790).
level (adj.): early 15c., "having an even surface," from level (n.). Meanings "lying on or constituting a horizontal surface" and "lying in the same horizontal plane" (as something else) are from 1550s. To do one's level best is U.S. slang from 1851, from level in the sense "well-aimed, direct, straight." Related: Levelly.
level (v.): mid-15c., "to make level" (transitive), from level (n.). From c. 1600 as "to bring to a level." Intransitive sense "cease increasing" is from 1958. Meaning "to aim (a gun)" is late 15c. Slang sense of "tell the truth, be honest" is from 1920. To level up "to rise" is attested by 1863.
A word here as to the misconception labored under by our English neighbor; he evidently does not understand the American manner of doing things. We never level down in this country; we are always at work on the up grade. "Level up! Level up!" is the motto of the American people. [James E. Garretson, "Professional Education," in "The Dental Cosmos," Philadelphia, 1865]
Modern use is mostly from computer gaming (2001). To level off "cease rising or falling" is from 1920, originally in aviation. Related: Levelled; levelling.
level-headed (adj.): also levelheaded, "sensible, shrewd," 1869, from level (adj.) + head (n.). The notion is of "mentally balanced." Related: Levelheadedness.
leveller (n.): also leveler, 1590s, someone or something that levels or makes even; agent noun from level (v.). In English history, from 1640s (with initial capital) as the name of a political party of the time of Charles I that advocated abolishing all differences of position and rank.
lever (n.): "simple machine consisting of a rigid piece acted upon at different points by two forces," c. 1300, from Old French levier (12c.) "a lifter, a lever, crowbar," agent noun from lever "to raise" (10c.), from Latin levare "to raise," from levis "light" in weight, "not heavy," also, of motion, "quick, rapid, nimble;" of food, "easy to digest;" figuratively "slight, trifling, unimportant; fickle, inconsistent;" of punishments, etc., "not severe."

This is from PIE root *legwh- "light, having little weight; easy, agile, nimble" (source also of Sanskrit laghuh "quick, small;" Greek elakhys "small," elaphros "light;" Old Church Slavonic liguku, Lithuanian lengvas "light;" Old Irish lu "small," laigiu "smaller, worse;" Gothic leihts, Old English leoht "not dark"). As a verb, 1856, from the noun.
leverage (n.): 1724, "action of a lever," from lever (n.) + -age. Meaning "power or force of a lever" is from 1827; figurative sense "advantage for accomplishing a purpose" is from 1858. The financial sense is attested by 1933, American English; as a verb in the financial sense by 1956. Related: Leveraged; leverages; leveraging.
leveret (n.): "young hare," early 15c., from Old French levrat, diminutive of levre (12c., Modern French lièvre) "hare," from Latin lepore, from lepus "a hare." "According to Pliny, [Greek leberis] 'rabbit' is from Massilia. This has given rise to the idea that lepus is an Iberian loanword in Latin, which is possible but not certain." [de Vaan]
Levi: masc. proper name, biblical son of Jacob by Leah, from Hebrew lewi, literally "joining, pledging, attached," from stem of lawah "he joined."
leviathan (n.): late 14c., "sea monster, sea serpent," sometimes regarded as a form of Satan, from Late Latin leviathan, from Hebrew livyathan "dragon, serpent, huge sea animal," of unknown origin, perhaps from root l-w-h- "to wind, turn, twist," on the notion of a serpent's coils. If so, related to Hebrew liwyah "wreath," Arabic lawa "to bend, twist." Of powerful persons or things from c. 1600. Hobbes's use is from 1651.
An aquatic animal mentioned in the Old Testament. It is described in Job xli. apparently as a crocodile; in Isa. xxvii 1 it is called a piercing and a crooked serpent; and it is mentioned indefinitely in Ps. lxxiv. 14 as food and Ps. civ. 26. [Century Dictionary]
levirate (n.): custom by which the male next-of-kin of a dead man was bound to marry his widow, 1725, with -ate (2) + Latin levir "brother-in-law," from PIE *daiwer- "husband's brother" (source also of Greek daer, Sanskrit devara, Old English tacor, Old High German zeihhur). Related: Leviratic; leviratical.
Levis (n.): 1926, American English, originally Levi's, from the name of the original manufacturer, Levi Strauss and Company of San Francisco. The Bavarian-born Strauss had been a dry-goods merchant in San Francisco since 1853; his innovation was the copper rivets at strain points, patented in 1873 according to the company. A cowboy's accessory at first, hip or fashionable from c. 1940s.
levitate (v.): 1670s, "to rise by virtue of lightness" (intransitive), from Latin levitas "lightness," on the model of gravitate (compare levity). Transitive sense of "raise (a person) into the air, cause to become buoyant" (1870s) is mainly from spiritualism. Related: Levitated; levitating.
levitation (n.): 1660s, noun of action from Latin levitas "lightness" (see levitate) + -ion.
Levite (n.): c. 1300, "descendant of Levi in the Old Testament, one of the tribe of Levi," a portion of which acted as assistant priests in the Temple, from Late Latin Levites, from Greek Leuites (see Leviticus). Related: Levitic; levitical.
Leviticus: third book of the Pentateuch, c. 1400, from Late Latin Leviticus (liber), literally "book of the Levites," from Greek to Leuitikon biblion, from Leuites, from Hebrew Lewi (see Levi). Properly the part of the Pentateuch dealing with the function of the priests who were of the tribe of Levi (a portion of the tribe acted as assistants to the priests in the temple-worship). The Hebrew title is Torath Kohanim, literally "the law of the priests."
Levittown: used figuratively for "generic suburban tract housing," American English, from the vast planned real estate developments built by the firm Levitt & Sons Inc., the first on Long Island, 1946-51 (more than 17,000 homes), the second north of Philadelphia (1951-55).
levity (n.): 1560s, "want of seriousness, frivolity," from French levite, from Latin levitatem (nominative levitas) "lightness," literal and figurative; "light-mindedness, frivolity," from levis "light" in weight, from PIE root *legwh- "lightness" (see lever). In old science (16c.-17c.), the name of a force or property of physical bodies, the opposite of gravity, causing them to tend to rise.
levo-: also laevo-, word-forming element meaning "toward the left," from French lévo-, from Latin laevus "left," from PIE root *laiwo- "left" (see left (adj.)).
levy (v.): early 13c., "to raise or collect" (by authority or compulsion), from Anglo-French leve, from Old French levée "act of raising," noun use of fem. past participle of lever "to raise" (see lever, and compare levee). Originally of taxes, later of men for armies (c. 1500). Related: Levied; levying.
levy (n.2): 1829, colloquial shortening of elevenpence (see eleven). In U.S. before c. 1860, a Spanish real or an equivalent amount of some other money (about 12 and a half sense).
levy (n.1): "an act of levying, a raising or collecting of anything" (a tax, debt, fine, etc.), early 15c., from Anglo-French leve (mid-13c.), Old French levée "a raising, lifting; levying," noun use of fem. past participle of lever "to raise" (see lever).
lewd (adj.): Middle English leued, from Old English læwede "nonclerical, unlearned," of uncertain origin but according to OED probably ultimately from Vulgar Latin *laigo-, from Late Latin laicus "belonging to the people" (see lay (adj.)).

Sense of "unlettered, uneducated" (early 13c.) descended to "coarse, vile, lustful" by late 14c. In Middle English often paired alliteratively with learned. It also was a noun in Old English, "layman;" for nouns, Elizabethan English made lewdster, lewdsby. Related: Lewdly; lewdness.
Lewis: masc. proper name, Anglo-French form of French Louis (see Louis).
lex talionis (n.): 1590s, legal Latin, "law of retaliation," an eye for an eye, a tooth for a tooth, from lex "law" (see legal) + talionis, genitive of talio "exaction of payment in kind" (see retaliation). Not related to talon. Other legal Latin phrases include lex domicilii "the law of the place where the person resides," lex fori "law of the place in which an action is brought."
lexeme (n.): 1937, from lexicon + -eme, ending abstracted from morpheme. Related: Lexemic.
lexical (adj.): "relating to the vocabulary of a language," 1833, from a Latinized form of Greek lexikos "pertaining to words" (see lexicon) + -al (1). Related: Lexically.
lexico-: word-forming element, "pertaining to words or lexicons; lexical and," from Latinized form of Greek lexikos "pertaining to words" (see lexicon).
lexicographer (n.): "a dictionary-writer," 1650s, perhaps based on French lexicographe "lexicographer," from a Latinized form of Greek lexikographos, from lexikon "wordbook" (see lexicon) + -graphos "writer," from graphein "to write" (see -graphy).
lexicography (n.): "the writing of dictionaries," 1670s, from lexico- + -graphy. Related: Lexicographic; lexicographical.
lexicology (n.): "the study of words," including form, history, and sense, 1828, from lexico- + -logy. Related: Lexicology; lexicologist.
lexicon (n.): c. 1600, "a dictionary, a word-book," from Middle French lexicon or directly from Modern Latin lexicon, from Greek lexikon (biblion) "word (book)," from neuter of lexikos "pertaining to words," from lexis "word, a speaking, saying, speech, phrase; way of speaking, diction," from legein "to say" (see lecture (n.)).

Especially of dictionaries of Greek, Syriac, Hebrew, or Arabic, because these typically were written in Latin, and in Modern Latin lexicon (not dictionarius) was the preferred name for a word-book. The modern sense of "vocabulary proper to some sphere of activity" (1640s) is a figurative extension.
ley (n.): "line of a prehistoric track; alignment of natural and artificial features," 1922 [Alfred Watkins], apparently a variant of lea. Popular topic in Britain in 1920s and 30s and again 1960s-70s.
Leyden: modern Leiden, city in Holland, said to be from Germanic *leitha- "canal." Leyden jar, phial used for accumulating and storing static electricity (1755), so called because it was first described (in 1746) by physicist Pieter van Musschenbroek (1692-1761) of Leyden.
lez: also les; by 1929, colloquial shortening of lesbian, altered in spelling to reflect pronunciation.
Lhasa: capital of Tibet, Tibetan, literally "city of the gods," from lha "god" + sa "city." The Lhasa apso type of dog is so called from 1935 in English, from Tibetan, literally "Lhasa terrier." Earlier name in English was Lhasa terrier (1894).
liability (n.): 1790, originally a term in law; "condition of being legally liable" (the sense in limited liability); see liable + -ity. General sense is from 1809; meaning "thing for which one is liable" is first attested 1842. Related: Liabilities.
liable (adj.): mid-15c., "bound or obliged by law," probably from Anglo-French *liable, from Old French lier "to bind, tie up, fasten, tether; bind by obligation" (12c.), from Latin ligare "to bind, to tie" (see ligament). With -able. Perhaps from an unattested word in Old French or Medieval Latin. General sense of "exposed to" (something undesirable) is from 1590s. Incorrect use for "likely" is attested by 1850.
liaise (v.): 1928, back-formation from liaison. Said to have been a coinage of British military men in World War I. Related: Liaised; liaising.
liaison (n.): 1640s, originally in English as a cookery term for a thickening agent for sauces, from French liaison "a union, a binding together" (13c.), from Late Latin ligationem (nominative ligatio) "a binding," from past participle stem of Latin ligare "to bind" (see ligament).

Sense of "intimate relations" (especially between lovers) is from 1806. Military sense of "cooperation between branches, allies, etc." is from 1816. The meaning "one who is concerned with liaison of units, etc." is short for liaison officer (1915).
liar (n.): "one who knowingly utters falsehoods," early 13c., from Old English leogere "liar, false witness, hypocrite," agent noun from Anglian legan, West Saxon leogan "be untruthful, lie" (see lie (v.1)). "The form in -ar is probably in imitation of the refashioned forms such as scholar for scoler and pillar for piler" [Barnhart]. A different formation yielded Dutch leugenaar, Old High German luginari, German Lügner, Danish lögner.
lib (n.): 1969, American English, shortening of liberation, used with possessives, originally in Women's Lib. Colloquial shortening libber for liberationist (n.) is attested from 1971.
libation (n.): late 14c., "pouring out of wine in honor of a god," from Latin libationem (nominative libatio) "a drink-offering," noun of action from past participle stem of libare "pour out (an offering)," from PIE *(s)leib- "to pour, drop" (source of Greek leibein "to pour, make a libation").

This is from an enlargement of the PIE root *lei- "to flow" (source also of Sanskrit riyati "to let run;" Greek aleison "a cup for wine, goblet;" Lithuanian lieju "to pour," lytus "rain;" Hittite lilai- "to let go;" Albanian lyse, lise "a stream;" Welsh lliant "a stream, a sea," llifo "to flow;" Old Irish lie "a flood;" Breton livad "inundation;" Gaelic lighe "a flood, overflow;" Gothic leithu "fruit wine;" Old Church Slavonic liti, lêju, Bulgarian leja "I pour;" Czech liti, leji, Old Polish lić "to pour"). Transferred sense of "liquid poured out to be drunk" is from 1751. Related: Libations.
libel (n.): c. 1300, "formal written statement, a writing of any kind," especially, in civil law, "plaintiff's statement of charges" (mid-14c.); from Old French libelle (fem.) "small book; (legal) charge, claim; writ; written report" (13c.), from Latin libellus "a little book, pamphlet; petition, written accusation, complaint," diminutive of liber "book" (see library). Meaning "false or defamatory statement" is from 1610s. Specific legal sense of "any published or written statement likely to harm a person's reputation" is first attested 1630s.
libel (v.): mid-15c., "make an initial statement setting out a plaintiff's case," from libel (n.), which see for sense development. Meaning "defame or discredit by libelous statements" is from c. 1600. Related: Libeled; libelled; libeling; libelling; libellant; libellee.
libelous (adj.): also libellous, "defamatory, containing that which exposes another to public hatred, contempt, or ridicule," 1610s, from libel (n.) + -ous. Related: Libelously; libelousness.
liberal (n.): 1820, "member of the progressive and reformist political party of Great Britain, an anti-Whig," from liberal (adj.). General meaning "person of liberal political principles or tendencies" (without reference to party) is by 1832; in reference to persons of a political ideology not conservative or fascist but short of socialism, from c. 1920. Also used from early 20c. of ministers from less-dogmatic Christian churches.
Conservative, n. A statesman who is enamored of existing evils, as distinguished from the Liberal, who wishes to replace them with others. [Ambrose Bierce, "Devil's Dictionary," 1911]