Online Etymology Dictionary

mopstick (n.): 1710, from mop (n.) + stick (n.).
moraine (n.): "ridge of rock deposited by a glacier," 1789, from French moraine (18c.), from Savoy dialect morena "mound of earth," from Provençal morre "snout, muzzle," from Vulgar Latin *murrum "round object," of unknown origin, perhaps from a pre-Latin Alpine language. Related: Morainal; morainic.
moral (adj.): mid-14c., "pertaining to character or temperament" (good or bad), from Old French moral (14c.) and directly from Latin moralis "proper behavior of a person in society," literally "pertaining to manners," coined by Cicero ("De Fato," II.i) to translate Greek ethikos (see ethics) from Latin mos (genitive moris) "one's disposition," in plural, "mores, customs, manners, morals," of uncertain origin. Perhaps sharing a PIE root with English mood (1).

Meaning "morally good, conforming to moral rules," is first recorded late 14c. of stories, 1630s of persons. Original value-neutral sense preserved in moral support, moral victory (with sense of "pertaining to character as opposed to physical action"). Related: Morally.
moral (n.): "moral exposition of a story," c.1500, from moral (adj.) and from French moral and Late Latin morale.
morale (n.): 1752, "moral principles or practice," from French morale "morality, good conduct," from fem. of Old French moral "moral" (see moral (adj.)). Meaning "confidence" (especially in a military context) first recorded 1831, from confusion with French moral (French distinguishes le moral "temperament" and la morale "morality").
moralist (n.): "moral person," 1620s; "teacher of morals," 1630s, from moral (adj.) + -ist.
moralistic (adj.): 1845; from moralist + -ic. Related: Moralistically.
morality (n.): late 14c., "moral qualities," from Old French moralité "moral (of a story); moral instruction; morals, moral character" (13c.) and directly from Late Latin moralitatem (nominative moralitas) "manner, character," from Latin moralis (see moral (adj.)). Meaning "goodness" is attested from 1590s.
Where there is no free agency, there can be no morality. Where there is no temptation, there can be little claim to virtue. Where the routine is rigorously proscribed by law, the law, and not the man, must have the credit of the conduct. [William H. Prescott, "History of the Conquest of Peru," 1847]
moralize (v.): c.1400, "expound or interpret spiritual or moral significance," from Old French moraliser and directly from Late Latin moralizare, from moralis (see moral (adj.)). Related: Moralized; moralizing.
morals (n.): "a person's moral qualities," 1610s, plural of moral (n.).
morass (n.): "wet, swampy tract," 1650s, from Dutch moeras "marsh, fen," from Middle Dutch marasch, from Old French marais "marsh," from Frankish, possibly from West Germanic *marisk, from Proto-Germanic *mariskaz "like a lake," from *mari "sea" (see mere (n.)). The word was influenced in Dutch by moer "moor" (see moor (n.)). Figurative use is attested from 1867. Replaced earlier mareis (early 14c.; see marish).
moratoria (n.): Latin plural of moratorium.
moratorium (n.): 1875, originally a legal term for "authorization to a debtor to postpone payment," from neuter of Late Latin moratorius "tending to delay," from Latin morari "to delay," from mora "pause, delay," from PIE *mere- "to hinder, delay." The word didn't come out of italics until 1914. General sense of "a postponement, deliberate temporary suspension" is first recorded 1932. Related: Moratorial.
Moravia: region in central Europe, Medieval Latin, named for River Morva (German March, Latin Marus), which runs through it.
Moravian: 1550s (n.); 1610s (adj.), from Moravia. From 1746, in reference to the Protestant sect founded in the former German state of Moravia (now in Czech Republic). Related: Moravianism.
moray (n.): 1620s, from Portuguese moreia, from Latin muraena "sea eel, lamprey," from Greek smyraina, from smyros "sea eel."
morbid (adj.): 1650s, "of the nature of a disease, indicative of a disease," from Latin morbidus "diseased," from morbus "sickness, disease, ailment, illness," from root of mori "to die," which is possibly from PIE root *mer- "to rub, pound, wear away" (cf. Sanskrit mrnati "crushes, bruises;" Greek marainein "to consume, exhaust, put out, quench," marasmus "consumption"). Transferred use, of mental states, is from 1777. Related: Morbidly; morbidness.
morbidity (n.): 1721, from morbid + -ity.
mordacious (adj.): "given to biting," 1640s (originally figurative), from Latin mordac-, stem of mordax, from mordere "to bite," perhaps from PIE root (s)mer- "to rub away, harm" (see smart (v.)). Related: Mordacity.
mordant (adj.): late 15c., "caustic" (of words, speech), from Middle French mordant, literally "biting," present participle of mordre "to bite," from Latin mordere "to bite, bite into; nip, sting;" figuratively "to pain, cause hurt" (see mordacious). Related: Mordantly. The noun sense in dyeing is first recorded 1791; the adjective in this sense is from 1902. Related: Mordancy; mordantly.
Mordecai: masc. proper name, biblical cousin of Esther, from Hebrew Mordekhay, from Akkad. Marduk, chief god of the city of Babylon.
more (adj.): Old English mara "greater, more, stronger, mightier," used as a comparative of micel "great" (see mickle), from Proto-Germanic *maizon- (cf. Old Saxon mera, Old Norse meiri, Old Frisian mara, Middle Dutch mere, Old High German mero, German mehr), from PIE *meis- (cf. Avestan mazja "greater," Old Irish mor "great," Welsh mawr "great," Greek -moros "great," Oscan mais "more"), from root *me- "big." Sometimes used as an adverb in Old English ("in addition"), but Old English generally used related ma "more" as adverb and noun. This became Middle English mo, but more in this sense began to predominate in later Middle English.
"Take some more tea," the March Hare said to Alice, very earnestly.

"I've had nothing yet," Alice replied in an offended tone, "so I can't take more."

"You mean you can't take less," said the Hatter: "it's very easy to take more than nothing."
More or less "in a greater or lesser degree" is from early 13c.; appended to a statement to indicate approximation, from 1580s.
morel (n.): type of edible mushroom, 1670s, from French morille (16c.), of uncertain origin, apparently from Germanic; cf. Old High German morhilo (German Morchel), diminutive of morha "root of a tree or plant," from Proto-Germanic *murhon- (cf. Old English more, German möhre "carrot").
morello (n.): kind of bitter cherry, 1640s, of uncertain origin, perhaps ultimately from Latin amarus "bitter." Earlier form was morell (1610s).
moreover (adv.): late 14c., in phrase and yit more ouer "there is more to say;" from more (adv.) + over (adv.). Written as one word from late 14c.
mores (n.): "customs," 1907, from Latin mores "customs, manners, morals" (see moral (adj.)).
Moresco (adj.): 1550s, from Italian moresco, from Moro (see Moor).
Morgan: surname, a very old Celtic name. As a type of horse, 1840, named for Justin Morgan (1747-1798), Vermont horse-breeder and music teacher; the breed was developed from a stallion he owned.
morganatic (adj.): 1727, from French morganatique (18c.), from Medieval Latin matrimonium ad morganaticam "marriage of the morning," probably from Old High German *morgangeba (Middle High German morgengabe) "morning gift," corresponding to Old English morgengifu (see morn + gift). In an unequal marriage between a man of royal blood and a common woman, this was a gift traditionally given to the wife on the morning after consummation, representing the only share she and her children may claim in the husband's estate. Also known as left-handed marriage, because the groom gives the bride his left hand instead of his right, but sometimes this latter term is used of a class of marriage (especially in Germany) where the spouse of inferior rank is not elevated, but the children inherit rights of succession. Related: Morganatically.
morgen (n.): old measure of land in Holland (hence also in South Africa and colonial New York and New Jersey), roughly two acres, probably identical with Dutch morgen "morning" (see morn) and meaning "the amount of land one man can plow in a morning."
morgue (n.): "mortuary," 1821, from French Morgue, originally a specific building in Paris where bodies were exposed for identification:
There is, in the most populous part of the French metropolis, an establishment entitled La Morgue, destined for the reception and exposition of bodies drowned in the Seine, and caught in nets, which are placed in different parts of the river for that purpose. The object of this exposition is, that the deceased may be recognised by their friends or relatives, and receive the rights of sepulture accordingly. The Morgue is open at all hours of the day, to passengers of every description, and often displays at a time, five or six horrible carcasses stretched, without covering, on an inclined platform, and subjected to the promiscuous gaze of the mob. ["American Review," January 1811]
Before that it was the place where new prisoners were displayed to keepers to establish their identification. Thus the name is believed to be probably from French morgue "haughtiness," originally "a sad expression, solemn look," from Old French morguer "look solemnly," from Vulgar Latin *murricare "to make a face, pout," from *murrum "muzzle, snout." The 1768 Dictionnaire Royal François-Anglois Et Anglois-François defines French morgue both as "A proud, big, haughty or stately look, stare, surliness, or surly look" and "A little gratel room wherein a new prisoner is set, and must continue some hours, that the Jailer's ordinary servants may the better take notice of his face."

Adopted as a general term in U.S., 1880s, replacing earlier dead house, etc. In newspaper slang, "collection of pre-written obituary material of living persons" (1903), hence "library of clips, photos, etc.," 1918.
moribund (adj.): 1721, "about to die," from Middle French moribund (16c.), from Latin moribundus "dying, at the point of death," from mori "to die" (see mortal (adj.)). Figurative sense of "near an end" is from 1837. Related: Moribundity.
Morisco (adj.): 1550s, from Spanish morisco, from Moro (see Moor).
morituri te salutant: Latin, literally "those about to die salute you," words addressed to emperor by gladiators upon entering the arena. Third person singular is moriturus te salutat, first person singular is moriturus te saluto.
Mormon (n.): 1830, coined by religion founder Joseph Smith (1805-1844) in Seneca County, N.Y., from Mormon, supposed prophet and author of "The Book of Mormon," explained by Smith as meaning more mon, from English more + Egyptian mon "good." As an adjective by 1842. Related: Mormonism.
morn (n.): contracted from Middle English morwen, from Old English (Mercian) margen (dative marne), earlier morgen (dative morgne) "morning, forenoon, sunrise," from Proto-Germanic *murgana- "morning" (cf. Old Saxon morgan, Old Frisian morgen, Middle Dutch morghen, Dutch morgen, Old High German morgan, German Morgen, Gothic maurgins), from PIE *merk-, perhaps from root *mer- "to blink, twinkle" (cf. Lithuanian mirgeti "to blink").
morning (n.): mid-13c., morn, morewen (see morn) + suffix -ing, on pattern of evening. Originally the time just before sunrise. As an adjective from 1530s. Morning after in reference to a hangover is from 1884; in reference to a type of contraception, attested from 1867. Morning sickness as a symptom of pregnancy is from 1793 (Old English had morgenwlætung). Morning glory is from 1814, in reference to the time the flowers open. Morning star "Venus in the east before sunrise" is from 1530s (Old English had morgensteorra "morn-star"). As a greeting, short for good morning, attested by 1895.
Moro: "Muslim Malay of the Philippines," 1886, from Spanish Moro, literally "Moor" (see Moor).
morocco (n.): "kind of fine flexible leather," 1630s, short for Morocco leather, from Morocco, the country in northwest Africa, where the tanned leather first was made.
Morocco: country in northwest Africa, from Italian, from Berber Marrakesh (properly the name of the city of Marrakesh), from Arabic Maghrib-al-Aqca "Extreme West." Cf. French Maroc, German Marokko. In English, the first vowel has been altered, apparently by influence of Moor. Related: Moroccan.
moron (n.): 1910, medical Latin, from Greek (Attic) moron, neuter of moros "foolish, dull, sluggish, stupid," probably cognate with Sanskrit murah "idiotic." Latin morus "foolish" is a loan-word from Greek. Adopted by the American Association for the Study of the Feeble-minded with a technical definition "adult with a mental age between 8 and 12;" used as an insult since 1922 and subsequently dropped from technical use. Linnæus had introduced morisis "idiocy."
The feeble-minded may be divided into: (1) Those who are totally arrested before the age of three so that they show the attainment of a two-year-old child or less; these are the idiots. (2) Those so retarded that they become permanently arrested between the ages of three and seven; these are imbeciles. (3) Those so retarded that they become arrested between the ages of seven and twelve; these were formerly called feeble-minded, the same term that is applied to the whole group. We are now proposing to call them morons, this word being the Greek for "fool." The English word "fool" as formerly used describes exactly this grade of child--one who is deficient in judgment or sense. [Henry H. Goddard, in Journal of Proceedings and Addresses" of the National Education Association of the United States, July 1910]
moronic (adj.): 1911, from moron + -ic. Related: Moronically.
morose (adj.): 1530s "gloomy," from Latin morosus "morose, peevish, hypercritical, fastidious," from mos (genitive moris) "habit, custom" (see moral (adj.)). In English, manners by itself means "(good) manners," but here the implication in Latin is "(bad) manners." Related: Morosity.
morosely (adv.): 1650s, from morose + -ly (2).
moroseness (n.): 1660s, from morose + -ness. Earlier in the same sense was morosity (1530s), from Middle French morosité, from Latin morositas.
morph: as a noun, in biology, 1955; as a verb, in cinematic special effects, c.1987, short for metamorphosis. Related: Morphed; morphing. Earlier it was a slang shortening of morphine (1912).
morpheme (n.): "part of a word which contains the affixes," 1896, from German morpheme, coined 1895 by Polish-born linguist Jan Baudouin de Courtenay (1845–1929), from Greek morphe "form, shape" (see Morpheus), on analogy of phonème.
Morpheus: name for the god of dreams in Ovid, son of Sleep, literally "the maker of shapes," from Greek morphe "form, shape, figure," especially "a fine figure, a beautiful form; beauty, fashion, outward appearance," perhaps from PIE *merph-, a possible Greek root meaning "form." Related: Morphean. Cf. Morpho, an epithet of Aphrodite, literally "shapely."
morphic (adj.): 1826, from Greek morphe "form, shape" (see Morpheus) + -ic.
morphine (n.): chief alkaloid of opium, 1828, from French morphine or German Morphin (1816), name coined by German apothecary Friedrich Sertürner (1783-1840) in reference to Latin Morpheus, Ovid's name for the god of dreams, from Greek morphe "form, shape, beauty, outward appearance," perhaps from PIE *merph-, a possible Greek root meaning "form," of unknown origin. So called because of the drug's sleep-inducing properties.