Online Etymology Dictionary

lotion (n.): c. 1400, loscion, "liquid preparation for application to the skin," from Old French lotion (14c.), from Latin lotionem (nominative lotio) "a washing," noun of action from lotus (varied contraction of lavatus), popular form of lautus, past participle of lavere "to wash" (from PIE root *leue- "to wash").
lotophagi (n.): c. 1600, literally "lotus-eaters," from Greek lotophagoi (plural), from lotos (see lotus) + -phagos "eating" (from PIE root *bhag- "to share out, apportion; to get a share"). Related: Lotophagous.
lottery (n.): 1560s, "arrangement for an awarding of prizes by chance among those buying tickets," from Italian lotteria, from lotto "lot, portion, share," from a Germanic source. It is cognate with Old English hlot (see lot (n.)), and compare lotto. Middle French loterie is from Middle Dutch loterje, from the same Germanic source. Formerly they were typically used to raise money for some state or charitable purpose.
Lottie: also Lotta, fem. proper name, a diminutive of Charlotte.
lotto (n.): 1778 as the name of a bingo-like game of chance, from French loto and directly from Italian lotto "a lot," from or with Old French lot "lot, share, reward, prize" a borrowing from Frankish or some other Germanic source (compare Old English and Old Frisian hlot; see lot (n.)). In reference to the drawing of numbers to match those on the cards. Meaning "a lottery, a game of chance" is attested from 1827.
lotus (n.): a name given to various plants, not all related or alike, 1540s, from Latin lotus, from Greek lotos, a word used as a name for several plants before it came to mean Egyptian white lotus (a sense attested in English from 1580s). It is perhaps from Semitic (compare Hebrew lot "myrrh"). The plant bears a prominent part in the mythology of India, Egypt, China. The Homeric lotus later was held to be a North African shrub, from which "a kind of wine" [Century Dictionary] can be made. The name has also been given to several species of water-lilies and a bean that grows in water. The yogic sense is attested from 1848.

It was believed to induce a dreamy forgetfulness, hence lotus-eater "one who finds pleasure in a listless life" (1812) is from Greek lotophagoi, mentioned in "Odyssey," book IX (see lotophagi).
louche (adj.): "dubious, disreputable," 1819, from French louche "squinting," from Old French lousche, lois (12c.) "cross-eyed, squint-eyed, lop-sided," from Latin lusca, fem. of luscus "blind in one eye, one-eyed," from Proto-Italic *luk-sko- "with partial sight, visually handicapped," from PIE *luk- "to see" or *leuk- "light" [de Vaan].
loud (adv.): Old English hlude "loudly, noisily," from Proto-Germanic *khludai (source also of Dutch luid, German laut), from the source of loud (adj.).
loud (adj.): Middle English, from Old English hlud "noisy; making or emitting noise" (of voices, musical instruments, etc.), from Proto-Germanic *hludaz "heard" (source also of Old Frisian and Old Saxon hlud, Middle Dutch luut, Dutch luid, Old High German hlut, German laut "loud"), from PIE *klutos- (source also of Sanskrit srutah, Greek klytos "heard of, celebrated," Latin inclutus "renowned, famous," Armenian lu "known," Irish cloth "noble, brave," Welsh clod "praise, fame"), suffixed form of root *kleu- "to hear."

Of places, "noisy," from 1590s. Application to colors, garments, etc. ("flashy, showy") is by 1849. Also used colloquially of notably strong or bad smells. Paired with clear (adj.) at least since c. 1650.
loud-mouth (n.): also loudmouth, "loud or overly talkative person," 1872, from loud (adj.) + mouth (n.). As an adjective from 1660s; loud-mouth'd is from 1620s.
loud-speaker (n.): also loudspeaker, "device for amplifying sound using an electric current," 1898, from loud (adj.) + speaker (n.).
loudly (adv.): c. 1400, from loud + -ly (2).
loudness (n.): Old English hludnis "loudness, clamor;" see loud + -ness.
lough (n.): "a lake, pool," early 14c., Anglo-Celtic, representing a northern form of Irish and Gaelic loch, Welsh llwch, from PIE *laku- (see lake (n.1), and compare loch).
Louis: masc. proper name, from French Louis, from Old French Loois, probably via Medieval Latin Ludovicus, a Latinization of Old High German Hluodowig, literally "famous in war" (cognate with Clovis; for etymology see Ludwig).

As the name of a French gold coin 17c.-18c., short for Louis d'or, from the French kings of that name (originally Louis XIII) pictured on the coins. Louis-Quatorze (1855) refers to styles reminiscent of the time of King Louis XIV of France (1643-1715).
Louise: also Louisa, fem. proper name, from French, fem. of Louis.
Louisiana: French colony, from 1812 a U.S. state, named 1682 by French explorer la Salle for Louis XIV of France. The name originally applied to the entire Mississippi basin. Related: Louisianian. The Louisiana Purchase, accomplished in 1803, was so called by 1806.
lounge (n.): 1806 as "act of lounging;" 1830 as "couch on which one can lie at full length;" 1881 as "comfortable drawing room" (suitable for lounging); from lounge (v.). Earlier senses, now out of use, were "pastime" (1788), "place for gathering" (1775). Lounge lizard is by 1917, perhaps 1912, originally in reference to men who loitered in tea rooms to flirt.
lounge (v.): c. 1500, "to loll idly, act or rest lazily and indifferently, move indolently if at all," Scottish, a word of uncertain origin. Meaning "recline lazily" is from 1746. Perhaps [Barnhart] it is from French s'allonger (paresseusement) "to lounge about, lie at full length," from Old French alongier "lengthen," from Latin longus "long" (see long (adj.)).

Another etymology traces it through the obsolete noun lungis "slow, lazy person" (c. 1560), which is from French longis "an idle, stupid dreamer," a special application, for some obscure reason, in Old French of the proper name Longis, which is from Latin Longius, Longinus. In old mystery plays and apocryphal gospels, Longinus is the name of the centurion who pierces Christ's side with a spear; the name perhaps was suggested by Greek longe "a lance" in John xix.34. But popular etymology associated the name directly with long (adj.). Related: Lounged; lounging; lounger.
lounging (n.): 1790, verbal noun from lounge (v.). Lounge chair is from 1841.
loupe (n.): "watchmaker's magnifier," 1909, from French loupe.
lour (v.): "to frown," late 13c. variant of lower (v.2). Related: Loured; louring.
louse (n.): parasitic insect infesting human hair and skin, Old English lus, from Proto-Germanic *lus (source also of Old Norse lus, Middle Dutch luus, Dutch luis, Old High German lus, German Laus), from PIE *lus- "louse" (source also of Welsh lleuen "louse").

The meaning "obnoxious person" is from 1630s. The plural lice (Old English lys) shows effects of i-mutation. Grose ["Dictionary of the Vulgar Tongue," 1785] has louse ladder "A stitch fallen in a stocking."
louse (v.): late 14c., "to clear of lice," from louse (n.). Compare delouse. Related: Loused; lousing. To louse up "ruin, botch" first attested 1934, from a literal sense (in reference to bedding), from 1931.
lousy (adj.): mid-14c., lousi, "infested with lice," from louse (n.) + -y (2). Figurative use as a generic adjective of abuse dates from late 14c.; sense of "swarming with" (money, etc.) is American English slang from 1843. Related: Lousiness.
lout (n.): 1540s, "awkward fellow, boor, bumpkin," of uncertain origin. Perhaps a noun from a dialectal survival of Middle English louten (v.) "bow down" (c. 1300), from Old English lutan "bow low," from Proto-Germanic *lut- "to bow, bend, stoop" (source also of Old Norse lutr "stooping," which itself might also be the source of the modern English word).

According to Watkins this is from PIE *leud- "to lurk" (source also of Gothic luton "to deceive," Old English lot "deceit), also "to be small" (see little). Non-Germanic cognates probably include Lithuanian liudeti "to mourn;" Old Church Slavonic luditi "to deceive," ludu "foolish." Sense of "cad" is first attested 1857 in British schoolboy slang.
loutish (adj.): 1550s, from lout + -ish. Related: Loutishly; loutishness.
louver (n.): also louvre, early 14c., "domed turret-like structure atop a building to disperse smoke and admit light," from Old French lovier, a word of uncertain origin. One theory [OED, Barnhart] connects it to Medieval Latin *lodarium, which might be from a Germanic source (compare Old High German louba "upper room, roof;" see lobby). Skeat and Klein's sources suggest it is from French l'ouvert, literally "the open place," from le, definite article, + past participle of ouvrir "to open." Century Dictionary finds this "quite untenable."

Meaning "overlapping strips in a window" (to let in air but keep out rain) first recorded 1550s. The form has been influenced by apparently unrelated French Louvre, the name of the palace in Paris, which is said to be so named because its builder, Philip Augustus, intended it as a wolf kennel. Related: Louvered, louvred.
lovable (adj.): also loveable, mid-14c., from love (v.) + -able. Related: Lovably.
love (v.): Old English lufian "to feel love for, cherish, show love to; delight in, approve," from Proto-Germanic *lubojan (source also of Old High German lubon, German lieben), a verb from the root of love (n.). Weakened sense of "like" attested by c. 1200. Intransitive sense "be in love, have a passionate attachment" is from mid-13c. To love (someone) up "make out with" is from 1921. To love and leave is from 1885.
love (n.): Old English lufu "feeling of love; romantic sexual attraction; affection; friendliness; the love of God; Love as an abstraction or personification," from Proto-Germanic *lubo (source also of Old High German liubi "joy," German Liebe "love;" Old Norse, Old Frisian, Dutch lof; German Lob "praise;" Old Saxon liof, Old Frisian liaf, Dutch lief, Old High German liob, German lieb, Gothic liufs "dear, beloved"). The Germanic words are from PIE root *leubh- "to care, desire, love."

The weakened sense "liking, fondness" was in Old English. Meaning "a beloved person" is from early 13c. The sense "no score" (in tennis, etc.) is 1742, from the notion of playing for love (1670s), that is, for no stakes. Phrase for love or money "for anything" is attested from 1580s. The phrase no love lost (between two people) is ambiguous and was used 17c. in reference to two who love each other well (c. 1640) as well as two who have no liking for each other (1620s, the usual modern sense).

To fall in love is attested from early 15c.; to be in love with (someone) is from c. 1500. To make love is from 1570s in the sense "pay amorous attention to;" as a euphemism for "have sex," it is attested from c. 1950. Love scene is from 1630s. Love affair "a particular experience of love" is from 1590s. Love life "one's collective amorous activities" is from 1919, originally a term in psychological jargon. Love beads is from 1968. Love bug, imaginary insect, is from 1937. Love-handles is from 1960s.
"Even now," she thought, "almost no one remembers Esteban and Pepita but myself. Camilla alone remembers her Uncle Pio and her son; this woman, her mother. But soon we shall die and all memory of those five will have left the earth, and we ourselves shall be loved for a while and forgotten. But the love will have been enough; all those impulses of love return the love that made them. Even memory is not necessary for love. There is a land of the living and a land of the dead and the bridge is love, the only survival, the only meaning." [Thornton Wilder, "Bridge of San Luis Rey," 1927]
love-apple (n.): old name for "tomato," 1570s, corresponding to French pomme d'amour, German Liebesapfel, but the reason for the term remains obscure. One guess is that it is a corruption of Italian pomo de'Mori or Spanish pome dei Moro, literally "Moorish apple."
love-bird (n.): also lovebird, 1590s, small species of West African parrot, noted for the remarkable attention mating pairs pay to one another; figurative sense of "a lover" is attested from 1911.
Hold hands, you lovebirds. [Emil Sitka]
love-child (n.): "child born out of wedlock, child of illicit love," 1805, from love (n.) + child. Earlier was love brat (17c.).
love-hate (adj.): expressing ambivalent and strong feelings toward someone or something, 1935, originally in the jargon of psychology, from love + hate.
love-knot (n.): bow or ribbon tied in a particular way, as a love token, late 14c., from love (n.) + knot (n.).
love-letter (n.): mid-13c., from love (n.) + letter (n.).
love-longing (n.): c. 1300, luue langing, from love (n.) + longing (n.).
love-lorn (adj.): also lovelorn, "pining for love," 1630s, from love (n.) + lorn. It seems to be first in Milton.
love-making (n.): "courtship," mid-15c.; see love (n.) + make (v.). Phrase make love is attested from 1570s in the sense "pay amorous attention to;" as a euphemism for "have sex," it is attested from c. 1950.
love-seat (n.): 1904, from love (n.) + seat (n.).
love-song (n.): early 14c., from love (n.) + song (n.).
love-tap (n.): "gentle blow given affectionately," 1848, from love (n.) + tap (n.2).
loved (adj.): c. 1300, past-participle adjective from love (v.). Loved ones "friends and relations" (especially those deceased) is from 1862.
Lovelace (n.): "fine-mannered libertine" [Century Dictionary], from the name of the hero of Richardson's "Clarissa Harlowe" (1748).
loveless (adj.): early 14c., "feeling no love;" late 14c. "unloved, not attracting love," from love (n.) + -less. Attested from mid-13c. as a surname. Related: Lovelessly; lovelessness.
lovelily (adv.): "in a lovely way," early 14c., from lovely + -ly (2).
loveliness (n.): mid-14c., "lovableness," from lovely + -ness.
lovely (adj.): Old English luflic "affectionate, loving; loveable;" see love (n.) + -ly (1). Sense of "lovable on account of beauty, attractive" is from c. 1300; in modern use "applied indiscriminately to all pleasing material objects, from a piece of plum-cake to a Gothic cathedral" [George P. Marsh, "The Origin and History of the English Language," 1862]. As an expression of delight, 1610s.
lover (n.): "one who is enamored, person in love," early 13c., agent noun from love (v.). Old English had lufend for male lovers, lufestre for women. Meaning "one who has a predilection for" (a thing, concept, pursuit, etc.) is mid-14c. As a form of address to a lover, from 1911. Related: Loverly (adj., 1875); loverless (1824). Lover's quarrel is from 1660s; lover's leap, usually involving a local crag and a fanciful story, is from 1831; Lover's Lane for a remote spot popular with lovers is from 1881.