Online Etymology Dictionary

menopause (n.): 1852 (from 1845 as a French word in English), from French ménopause, from medical Latin menopausis, from Greek men (genitive menos) "month" (see moon (n.)) + pausis "a cessation, a pause," from pauein "to cause to cease" (see pause (n.)). Earlier it was change of life.
menorah (n.): 1886, from Hebrew menorah "candlestick," from Semitic stem n-w-r "to give light, shine" (compare Arabic nar "fire," manarah "candlestick, lighthouse, tower of a mosque," see minaret).
mens rea: Latin phrase meaning "guilty mind."
mens sana in corpore sano: c. 1600, Latin, literally "a sound mind in a sound body," a line found in Juvenal, "Satires," x.356.
Mens sana in corpore sano is a contradiction in terms, the fantasy of a Mr. Have-your-cake-and-eat-it. No sane man can afford to dispense with debilitating pleasures; no ascetic can be considered reliably sane. Hitler was the archetype of the abstemious man. When the other krauts saw him drink water in the Beer Hall they should have known he was not to be trusted. [A.J. Liebling, "Between Meals," 1962]
mensa (n.): "altar top," 1848, Latin, literally "table," also "meal, supper," and "altar, sacrificial table," hence used in Church Latin for "upper slab of a church altar" (see mesa). With a capital M-, the name of an organization for people of IQs of 148 or more founded in England in 1946, the name chosen, according to the organization, to suggest a "round table" type group. The constellation was originally Mons Mensae "Table Mountain."
La Caille, who did so much for our knowledge of the southern heavens, formed the figure from stars under the Greater Cloud, between the poles of the equator and the ecliptic, just north of the polar Octans; the title being suggested by the fact that the Table Mountain, back of Cape Town, "which had witnessed his nightly vigils and daily toils," also was frequently capped by a cloud. [Richard Hinckley Allen, "Star Names and Their Meanings," London: 1899]
mensal (adj.1): "monthly," 1860, from Latin mensis "month" (see moon (n.)) + -al (1).
mensal (adj.2): "pertaining to or used at a table," mid-15c., from Late Latin mensalis, from Latin mensa "table" (see mesa).
mensch (n.): "person of strength and honor," 1907, from Yiddish, from German Mensch, literally "man, person," from Old High German mennisco "human," from Proto-Germanic adjective *manniska- "human" (see mannish).
menses (n.): "monthly discharge of blood from the uterus," 1590s, from Latin menses, plural of mensis "month" (see moon (n.)).
Menshevik (adj.): 1907, from Russian men'shevik, from men'she "lesser" (comparative of malo "little," from PIE root *mei- (2) "small;" see minus) + -evik "one that is." So called by Lenin because they were a minority in the party. Earlier used in reference to the minority faction of the Social-Democratic Party, when it split in 1903. As a noun from 1917. Russian plural mensheviki occasionally was used in English.
menstrual (adj.): late 14c., "pertaining to menses," also (in astronomy) "monthly," from Old French menstruel, from Latin menstrualis "monthly," especially "of or having monthly courses," from menstruus "of a month, every month, monthly, pertaining to a month," from mensis "month" (see moon (n.)).
menstruate (v.): 1680s, probably a back-formation from menstruation, or else from Latin menstruatus, past participle of menstruare. Related: Menstruated; menstruating.
menstruation (n.): 1680s, from Late Latin menstruare, from menstruus "monthly" (see menstrual) + -ation. Old English equivalent was monaðblot "month-blood." Middle English had menstrue (n.), late 14c., from Old French menstrue, from Latin menstruum.
menstruous (adj.): 1530s, from French menstrueus, from Latin *menstruosus, from menstruum, from menstruus (adj.) "monthly," from mensis "month" (see moon (n.)).
mensurable (adj.): c. 1600, from Late Latin mensurabilis "able to be measured," from mensurare "to measure" (see measure (v.)). Related: Mensurably; mensurability.
mensural (adj.): "pertaining to measure, measurable," c. 1600, from Medieval Latin mensuralis, from Latin mensura "a measuring, measurement" (see measure (v.)).
mensuration (n.): "act of measuring," 1570s, from Middle French mensuration and directly from Late Latin mensurationem (nominative mensuratio) "a measuring," noun of action from past participle stem of mensurare "to measure" (see measure (v.)).
mental (adj.): early 15c., "pertaining to the mind," from Middle French mental, from Late Latin mentalis "of the mind," from Latin mens (genitive mentis) "mind," from PIE root *men- "to think" (source also of Sanskrit matih "thought, mind," Gothic gamunds, Old English gemynd "memory, remembrance;" see mind (n.)). Meaning "crazy, deranged" is from 1927, probably from combinations such as mental hospital.
mentalist (n.): 1782, from mental + -ist. Originally in reference to artistic taste; philosophical sense (from mentalism) is from 1900. Related: mentalistic.
mentality (n.): 1690s, from mental (adj.) + -ity. Rare before 20c.
mentally (adv.): 1660s, from mental + -ly (2).
mentation (n.): "mental function," 1850, from Latin ment- "mind" (see mental) + -ation.
menthol (n.): white crystalline substance, 1862, from German Menthol, coined 1861 by Alphons Oppenheim from Latin mentha "mint" (see mint (n.1)) + oleum "oil" (see oil (n.)). So called because it was first obtained from oil of peppermint.
mentholated (adj.): of cigarettes, 1933, from menthol + -ate (2).
mention (n.): c. 1300, "a note, reference," from Old French mencion "mention, memory, speech," from Latin mentionem (nominative mentio) "a calling to mind, a speaking of, a making mention," from root of Old Latin minisci "to think," related to mens (genitive mentis) "mind," from PIE root *men- (1) "think" (see mind (n.)).
mention (v.): 1520s, from mention (n.) or else from Middle French mentionner, from Old French mencion. Related: Mentioned; mentioning; mentionable. Don't mention it as a conventional reply to expressions of gratitude or apology is attested from 1840.
mentor (n.): "wise advisor," 1750, from Greek Mentor, friend of Odysseus and adviser of Telemachus (but often actually Athene in disguise) in the "Odyssey," perhaps ultimately meaning "adviser," because the name appears to be an agent noun of mentos "intent, purpose, spirit, passion" from PIE *mon-eyo- (source also of Sanskrit man-tar- "one who thinks," Latin mon-i-tor "one who admonishes"), causative form of root *men- "to think" (see mind (n.)). The general use of the word probably is via later popular romances, in which Mentor played a larger part than he does in Homer.
mentor (v.): 1888, from mentor (n.). Related: Mentored; mentoring.
menu (n.): 1837, from French menu de repas "list of what is served at a meal," from Middle French menu (adj.) "small, detailed" (11c.), from Latin minutus "small," literally "made smaller," past participle of minuere "to diminish," from root of minus "to diminish" (see minus). Computer usage is from 1967, from expanded sense of "any detailed list," first attested 1889.
meow (n.): representation of cat sound, 1842, earlier miaow, miau, meaw (1630s). Of imitative origin, compare French miaou, German miauen, Persian maw, Japanese nya nya, Arabic nau-nau, and Joyce's mrkgnao. In Chinese, miau means "cat." As a verb by 1630s, meaw, also meawle. Compare Old French miauer "to meow, caterwaul." Related: Meowed; meowing.
Mephisto: shortened form of Mephistopheles.
Mephistopheles: 1590s, the evil spirit to whom Faust sold his soul in the German legend, from German (1587), of unknown origin. According to the speculation of eminent Göthe scholar K.J. Schröer (1886) it is a compound of Hebrew mephitz "destroyer" + tophel "liar" (short for tophel sheqer, literally "falsehood plasterer;" see Job xiii:4). Klein writes that the names of devils in the Middle Ages "are in most cases derived from Hebrew."
mephitic (adj.): 1620s, "of poisonous smell," from Late Latin mephiticus, from Latin mephitis, mefitis "noxious vapor" (also personified as a goddess believed to have the power to avert it).
Mercalli: in reference to Mercalli scale, 1900, named for Italian geologist Giuseppe Mercalli (1850-1914), who invented it ("I Terremoti della Liguria e del Piemonte," Naples, 1897). It was a modification of the Rossi-Forel scale (1883).
mercantile (adj.): 1640s, from French mercantile (17c.), from Italian mercantile, from Medieval Latin mercantile, from Latin mercantem (nominative mercans) "a merchant," also "trading," present participle of mercari "to trade," from merx (see market (n.)). Mercantile system first appears in Adam Smith (1776).
mercantilism (n.): 1834, from French mercantilisme; see mercantile + -ism. Related: mercantilist.
Mercator: type of map projection, 1660s, invented by Flemish geographer Gerhard Kremer (1512-1594), who Latinized his surname, which means "dealer, tradesman," as Mercator (see merchant). He first used this type of map projection in 1568.
Mercedes: fem. proper name, from Spanish, abbreviation of Maria de las Mercedes "Mary of the Mercies," from plural of merced "mercy, grace," from Latin mercedem (nominative merces); see mercy.
Mercedes-Benz: motorcar brand first marketed 1926 after merger of two earlier companies. The first part of the name, Mercedes, marketed as a car name from 1901, chosen by Austrian manufacturer Emil Jellinek for his daughter, Mercedes (1889-1929). The Benz is from the other company, from name of Karl Benz, creator of the Benz Patent Motorwagen (1886). The surname is built from a familiar form of Berthold, Benedict, or Bernhard.
mercenary (n.): late 14c., "one who works only for hire," from Old French mercenaire "mercenary, hireling" (13c.) and directly from Latin mercenarius "one who does anything for pay," literally "hired, paid," from merces (genitive mercedis) "pay, reward, wages," from merx (see market (n.)).
mercenary (adj.): 1530s, from mercenary (n.), or in part from Latin mercenarius "hired, paid, serving for pay."
mercer (n.): early 12c., "dealer in textile," from Old French mercier "shopkeeper, tradesman," from Vulgar Latin *merciarius, from Latin merx (see market (n.)).
merchandise (n.): mid-13c., "trading, commerce;" mid-14c., "commodities of commerce, wares, articles for sale or trade," from Anglo-French marchaundise, Old French marcheandise "goods, merchandise; trade, business" (12c.), from marchaunt "merchant" (see merchant).
merchandise (v.): also merchandize, "to buy and sell; to market," late 14c.; see merchant + -ize. Meaning "promote the sale of goods" is from 1926. Related: Merchandising; merchandizing.
merchandiser (n.): 1590s, agent noun from merchandise (v.).
merchandizing (n.): late 14c., "goods, commodities," from present participle of merchandize. Meaning "trade, commerce" is from mid-15c. That of "promotion of goods for sale" is from 1922.
merchant (n.): c. 1200, from Anglo-French marchaunt "merchant, shopkeeper" (Old French marcheant, Modern French marchand), from Vulgar Latin *mercatantem (nominative *mercatans) "a buyer," present participle of *mercatare, frequentative of Latin mercari "to trade, traffic, deal in" (see market). Meaning "fellow, chap" is from 1540s; with a specific qualifier, and suggesting someone who deals in it (such as speed merchant "one who enjoys fast driving"), from 1914.
merchant (adj.): c. 1400, from merchant (n.) and from Old French marcheant (adj.).
Mercia: Anglo-Saxon kingdom of the Midlands, Latinized from Old English Mierce "men of the Marches," from mearc (see march (n.2)). Related: Mercian.
merciful (adj.): mid-14c.; see mercy + -ful. Related: Mercifully.