Online Etymology Dictionary

magnetize (v.): 1799, from magnet + -ize. Related: Magnetized; magnetizing. From 1785 in now-obsolete sense of "to mesmerize."
magneto (n.): 1882, short for magneto-electric machine (see magneto-).
magneto-: word-forming element meaning "magnetic, magnetism," from Greek magneto-, combining form of magnes (see magnet).
magneto-electric (adj.): also magnetoelectric, "characterized by electricity produced by magnets," 1831, from magneto- + electric.
magnetopause (n.): 1963, from magneto- in magnetosphere + pause (n.).
magnetosphere (n.): 1959, from magneto- + sphere. So called because in it the magnetic field of the earth plays a dominant role in the motion of particles.
magni-: word-forming element meaning "great," from Latin magni-, comb. form of magnus "great" (see magnate (n.)).
Magnificat (n.): c. 1200, from Latin third person singular of magnificare (see magnificence), from first words of the Virgin's hymn (Luke i:46, in Vulgate Magnificat anima mea dominum "My soul doth magnify the Lord") used as a canticle.
magnification (n.): early 15c., from Late Latin magnificationem (nominative magnificatio), noun of action from past participle stem of magnificare (see magnify).
magnificence (n.): mid-14c., "great-mindedness, courage," from Old French magnificence "splendor, nobility, grandeur," from Latin magnificentia "splendor, munificence," from stem of magnificus "great, elevated, noble, eminent," also "splendid, rich, fine, costly," literally "doing great deeds," from magnus "great" (see magnate) + root of facere "to make" (see factitious). Meaning "greatness, grandeur, glory" in English is from late 14c. That of "beauty, splendor, wealth" is 15c. As one of the Aristotelian and scholastic virtues, it translates Greek megaloprepeia "liberality of expenditure combined with good taste."
magnificent (adj.): mid-15c., from Old French magnificent, a back-formation from Latin magnificentior, comparative of magnificus "great, elevated, noble, distinguished," literally "doing great deeds" (see magnificence).
magnificently (adv.): "in a splendid manner," early 15c.; see magnificent + -ly (2).
magnifier (n.): 1540s, agent noun from magnify.
magnify (v.): late 14c., "to speak or act for the glory or honor (of someone or something)," from Old French magnefiier "glorify, magnify," from Latin magnificare "esteem greatly, extol, make much of," from magnificus "great, elevated, noble" (see magnificence). Meaning "use a telescope or microscope" is first attested 1660s, said to be a unique development in English. Related: Magnified; magnifying.
magniloquence (n.): 1620s, from Latin magniloquentia "elevated language, lofty style;" see magniloquent + -ence.
magniloquent (adj.): 1650s, a back-formation from magniloquence, or else from Latin magniloquentia "lofty style of language," from magniloquus "pompous in talk, vaunting, boastful," from comb. form of magnus "great" (see magnate) + -loquus "speaking," from loqui "to speak" (see locution).
magnitude (n.): c. 1400, "greatness of size or character," from Latin magnitudo "greatness, bulk, size," from magnus "great" (see magnate) + -tudo, suffix forming abstract nouns from adjectives and participles (see -tude). Meaning "size, extent" is from early 15c. Of stars, "brightness," from 1640s.
magnitudinous (adj.): 1789; see magnitude + -ous.
magnolia (n.): plant genus, 1748, from Magnolius, Latinized name of Pierre Magnol (1638-1715), French physician and botanist, professor of botany at Montpellier, + abstract noun ending -ia. As the name of a color, by 1931.
magnum (n.): 1788, "bottle containing two quarts of wine or spirits," from Latin magnum, neuter of magnus "great in size" (see magnate). Registered 1935 by Smith & Wesson Inc., of Springfield, Massachusetts, as the name of a powerful type of handgun.
magnum opus: "masterpiece, a person's greatest work," Latin, literally "great work" (see magnum + opus).
Magnus: Scandinavian masc. proper name, popular with early kings, the first to use it was Magnus I, king of Norway and Denmark (d.1047), who evidently took it in emulation of Charlemagne (Latin Carolus Magnus) under the impression that magnus (Latin, literally "great;" see magnate) was a personal name.
magpie (n.): the common European bird, known for its chattering, c. 1600, earlier simply pie (early 13c.); first element from Mag, nickname for Margaret, long used in proverbial and slang English for qualities associated generally with women, especially in this case "idle chattering" (as in Magge tales "tall tales, nonsense," early 15c.; also compare French margot "magpie," from Margot, pet form of Marguerite).

Second element, pie, is the earlier name of the bird, from Old French pie, from Latin pica "magpie," fem. of picus "woodpecker," from PIE root *(s)peik- "woodpecker, magpie" (source also of Umbrian peica "magpie," Sanskrit pikah "Indian cuckoo," Old Norse spætr, German Specht "woodpecker"); possibly from PIE root *pi-, denoting pointedness, of the beak, perhaps, but the magpie also has a long, pointed tail. The birds are proverbial for pilfering and hoarding, can be taught to speak, and have been regarded since the Middle Ages as ill omens.
Whan pyes chatter vpon a house it is a sygne of ryghte euyll tydynges. [1507]
Divination by number of magpies is attested from c. 1780 in Lincolnshire; the rhyme varies from place to place, the only consistency being that one is bad, two are good.
Magrib: "Barbary," from Arabic Maghrib, literally "the west," from gharaba "(the sun) has set."
maguey (n.): "agave," 1550s, from Spanish, from Taino, a native Haitian language.
Magus (n.): member of the ancient Persian priestly caste, late 14c., singular of magi (q.v.).
Magyar: "a Hungarian," 1797, the people's native name. As an adjective by 1828.
mah-jongg (n.): 1922, from dialectal Chinese (Shanghai) ma chiang, name of the game, literally "sparrows," from ma "hemp" + chiang "little birds." The game so called from the design of the pieces. It had a vogue in Europe and the U.S. 1922-23 and for a time threatened to supplant bridge in popularity.
maharajah (n.): also maharaja, 1690s, from Hindi, "great king," from Sanskrit maha "great" (from PIE root *meg- "great;" see magnate) + rajan "king" (see rajah). The fem. equivalent is maharani (1855).
maharishi (n.): Hindu sage or holy man, 1785, from Sanskrit, from maha "great," from PIE root *meg- "great" (see magnate) + rishi "inspired sage." In general use, a title for a popular spiritual leader.
mahatma (n.): 1884, literally "great-souled," from Sanskrit mahatman, from maha "great," from PIE root *meg- "great" (see magnate) + atman, "soul, principle of life," properly "breath" (see atman). In esoteric Buddhism, "a person of supernatural powers." In common use, as a title, a mark of love and respect. Said to have been applied to Gandhi (1869-1948) in 1915 by poet Rabrindranath Tagore.
Mahayana: type of Buddhism practiced in northern Asia, 1868, from Sanskrit, from maha "great," from PIE root *meg- "great" (see magnate) + yana "vehicle," from PIE root *ei- (1) "to go" (see ion).
Mahdi (n.): 1792, from Arabic mahdiy, literally "he who is guided aright," past participle of hada "to lead in the right way." Spiritual and temporal leader expected by some Muslims. Applied c. 1880 to insurrectionary leaders in the Sudan who claimed to be him. Related: Mahdism.
mahogany (n.): 1670s, from Spanish mahogani, of unknown origin; perhaps from the tree's native name in Maya (Honduras). As an adjective from 1730.
Mahomet: see Muhammad. Related: Mahometan.
Maia: Roman goddess of fertility, Latin Maia, literally "she who brings increase," related to magnus "great" (see magnate). Maia, one of the Pleiades, is from Greek Maia, daughter of Atlas, mother of Hermes, literally "mother, good mother, dame; foster-mother, nurse, midwife," said by Watkins to be from infant babbling (see mamma).
maid (n.): late 12c., "a virgin, a young unmarried woman," shortening of maiden (n.). Like that word, used in Middle English of unmarried men as well as women (as in maiden-man, c. 1200, used of both sexes, reflecting also the generic use of man). Domestic help sense is from c. 1300. In reference to Joan of Arc, attested from 1540s (French la Pucelle). Maid Marian, one of Robin Hood's companions, first recorded 1520s, perhaps from French, where Robin et Marian have been stock names for country lovers since 13c. Maid of Honor (1580s) originally was "unmarried lady of noble birth who attends a queen or princess;" meaning "principal bridesmaid" is attested from 1895. Maydelond (translating Latin terra feminarum) was "the land of the Amazons."
maiden (n.): Old English mægden, mæden "maiden, virgin, girl; maid, servant," diminutive of mægð, mægeð "virgin, girl; woman, wife," from Proto-Germanic *magadinom "young womanhood, sexually inexperienced female" (source also of Old Saxon magath, Old Frisian maged, Old High German magad "virgin, maid," German Magd "maid, maidservant," German Mädchen "girl, maid," from Mägdchen "little maid"), fem. variant of PIE root *maghu- "youngster of either sex, unmarried person" (source also of Old English magu "child, son, male descendant," Avestan magava- "unmarried," Old Irish maug "slave").
maiden (adj.): "virgin, unmarried," c. 1300, from maiden (n.). The figurative sense of "new fresh, first" (as in maiden voyage) is first recorded 1550s. Maiden name is from 1680s.
maidenhead (n.): c. 1200, from maiden (n.) + Middle English -hede (see -head). Compare also maidehede (c. 1200) "celibacy, virginity" (of men or women).
maidenhood (n.): Old English mægdenhad "maidenhood;" see maiden (n.) + -hood.
maidenly (adj.): mid-15c., from maiden (n.) + -ly (1).
maidservant (n.): 1520s, from maid (n.) + servant.
mail (n.1): "post, letters," c. 1200, "a traveling bag," from Old French male "wallet, bag, bundle," from Frankish *malha or some other Germanic source, from Proto-Germanic *malho- (source also of Old High German malaha "wallet, bag," Middle Dutch male "bag"), from PIE *molko- "skin, bag." Sense extension to "letters and parcels" (18c.) is via "bag full of letter" (1650s) or "person or vehicle who carries postal matter" (1650s). In 19c. England, mail was letters going abroad, while home dispatches were post. Sense of "personal batch of letters" is from 1844, originally American English.
mail (n.2): "metal ring armor," c. 1300, from Old French maille "link of mail, mesh of net," from Latin macula "mesh in a net," originally "spot, blemish," on notion that the gaps in a net or mesh looked like spots.
mail (n.3): "rent, payment," from Old English mal (see blackmail (n.)).
mail (v.): "send by post," 1828, American English, from mail (n.1). Related: Mailed; mailing; mailable. Mailing list attested from 1876.
mail-order (adj.): 1875, from mail (n.1) + order. Before television and the Internet, the bane of retailers and shop-owners.
The origin, foundation and principle of mail order trading is universally recognized as wrong. It was conceived in iniquity and brought forth in despair as the world's greatest destructive medium. Mail Order Trading was born in the brain of knaves and thieves who fired their building for insurance profits, then sold the salvaged and damaged stock to the unsuspecting sons of man in distant territory. [Thomas J. Sullivan, "Merchants and Manufacturers on Trial," Chicago, 1914]
mailbag (n.): also mail-bag, 1794, from mail (n.1) + bag (n.).
mailbox (n.): also mail-box, 1797, "box for mailbags on a coach," from mail (n.1) + box (n.1). Meaning "letterbox" is from 1853, American English.