Online Etymology Dictionary

memento mori (n.): "reminder of death," 1590s, Latin, literally "remember that you must die."
memo (n.): 1889, shortening of memorandum (q.v.).
memoir (n.): early 15c., "written record," from Anglo-French memorie "note, memorandum, something written to be kept in mind" (early 15c., Old French memoire), from Latin memoria (see memory). Meaning "person's written account of his life" is from 1670s.
memoirs (n.): "personal record of events," 1650s, plural of memoir.
memorabilia (n.): "things worth remembering," 1806, from Latin memorabilia "notable achievements," noun use of neuter plural of memorabilis "worthy of being remembered" (see memorable).
memorability (n.): 1660s, from memorable + -ity.
memorable (adj.): mid-15c., from Middle French mémorable, from Latin memorabilis "that may be told; worthy of being remembered, remarkable," from memorare "to bring to mind," from memor "mindful of" (see memory). Related: Memorably.
memorandum (n.): early 15c., from Latin memorandum "(thing) to be remembered," neuter singular of memorandus "worthy of remembrance, noteworthy," gerundive of memorare "to call to mind," from memor "mindful of" (see memory). Originally a word written at the top of a note, by 1540s it came to stand for the note itself. The Latin plural is memoranda. Compare also agenda.
memorial (adj.): late 14c., "memorable, excellent; remembered, committed to memory," from Old French memorial "mindful of, remembering," from Latin memorialis (adj.) "of or belonging to memory," from memoria "memory" (see memory).
memorial (n.): late 14c., "fame, renown, reputation," also "commemorative gesture, monument, or rite;" in general, "something by which the memory of a person, thing, or event is preserved," from Old French memorial "record, report," and directly from Late Latin memoriale "a memorial," noun use of neuter of Latin memorialis (adj.) "of or belonging to memory," from memoria "memory" (see memory). Meaning "memorial act, commemoration" is from mid-15c.
Memorial Day: used in a general sense is from 1830s; as a specific holiday commemorating U.S. war dead (originally Northern soldiers killed in the Civil War) it began informally in late 1860s. officially from 1869 among veterans' organizations.
memorialize (v.): 1798, from memorial + -ize. Related: Memorialized; memorializing. Earlier verb was simply memorial (1731).
memorious (adj.): 1590s, from French memorieux or directly from Medieval Latin memoriosus, from Latin memoria (see memory).
memorise (v.): chiefly British English spelling of memorize; for suffix, see -ize. Related: Memorised; memorising; memorisation.
memorization (n.): 1823 "memorialization," 1857 as "action of committing to memory;" noun of action from memorize (v.).
memorize (v.): 1590s, "commit to writing;" see memory + -ize. The meaning "commit to memory" is from 1838. Related: Memorized; memorizing.
memory (n.): mid-13c., "recollection (of someone or something); awareness, consciousness," also "fame, renown, reputation," from Anglo-French memorie (Old French memoire, 11c., "mind, memory, remembrance; memorial, record") and directly from Latin memoria "memory, remembrance, faculty of remembering," noun of quality from memor "mindful, remembering," from PIE root *(s)mer- (1) "to remember" (Sanskrit smarati "remembers," Avestan mimara "mindful;" Greek merimna "care, thought," mermeros "causing anxiety, mischievous, baneful;" Serbo-Croatian mariti "to care for;" Welsh marth "sadness, anxiety;" Old Norse Mimir, name of the giant who guards the Well of Wisdom; Old English gemimor "known," murnan "mourn, remember sorrowfully;" Dutch mijmeren "to ponder"). Meaning "faculty of remembering" is late 14c. in English.
I am grown old and my memory is not as active as it used to be. When I was younger I could remember anything, whether it had happened or not; but my faculties are decaying now and soon I shall be so I cannot remember any but the things that never happened. It is sad to go to pieces like this, but we all have to do it. [Mark Twain, "Autobiography"]
Computer sense, "device which stores information," is from 1946. Related: Memories.
Memphis: ancient city of Egypt, from Greek form of Egyptian Mennefer, literally "his beauty," from men "his" + nefer "beauty" (as in Queen Nefertiti, literally "Beauty has Come"). A reference to pharaoh Pepi I (24c. B.C.E.). The city in Tennessee, U.S., was so named 1826 for obscure reasons. Related: Memphian (1590s); Memphitic (1580s).
men (n.): plural of man (n.). To separate the men from the boys in a figurative sense is from 1943; earliest uses tend to credit it to U.S. aviators in World War II.
One of the most expressive G.I. terms to come out of the late strife was "that's where they separate the men from the boys" -- so stated by American aviators leaning from their cockpits to observe a beach-landing under fire on some Pacific island far below. ["Arts Magazine," 1947]
menace (n.): c. 1300, "declaration of hostile intent," also "act of threatening," from Old French menace "menace, threat" (9c.), from Vulgar Latin minacia "threat, menace" (also source of Spanish amenaza, Italian minaccia), singular of Latin minaciæ "threatening things," from minax (genitive minacis) "threatening," from minari "threaten, jut, project," from minæ "threats, projecting points," from PIE root *men- (2) "to project" (see mount (n.1)). Applied to persons from 1936.
menace (v.): c. 1300, from Old French menacer "threaten, urge" (11c.), Anglo-French manasser, from Vulgar Latin *minaciare "to threaten," from minacia (see menace (n.)). Related: Menaced; menacing.
menacing (adj.): 1540s, present participle adjective from menace (v.). Related: Menacingly.
menage (n.): 1690s, "management of a household, domestic establishment," from French ménage, from Old French manage "household, family dwelling" (12c.), from Vulgar Latin *mansionaticum "household, that which pertains to a house," from Latin mansionem "dwelling" (see mansion). Now generally used in suggestive borrowed phrase ménage à trois (1891), literally "household of three." Borrowed earlier as mayngnage, maynage and in the sense "members of a household, a man's household" (c. 1300); but this was obsolete by c. 1500.
menage a trois (n.): 1891, see menage.
menagerie (n.): "collection of wild animals kept in captivity," 1712, from French ménagerie "housing for domestic animals" (16c.), from Old French manage (see menage).
menarche (n.): 1896, from German menarche (1895), from Greek men (genitive menos) "month" (see moon (n.)) + arkhe "beginning" (see archon).
mend (v.): c. 1200, "to repair," from a shortened form of Old French amender (see amend). Meaning "to put right, atone for, amend (one's life), repent" is from c. 1300; that of "to regain health" is from early 15c. Related: Mended; mending.
mend (n.): early 14c., "recompense, reparation," from mend (v.). Meaning "act of mending; a repaired hole or rip in fabric" is from 1888. Phrase on the mend attested from 1802.
mendable (adj.): 1530s, from mend (v.) + -able.
mendacious (adj.): 1610s, from Middle French mendacieux, from Latin mendacium "a lie, untruth, falsehood, fiction," from mendax (genitive mendacis) "lying, deceitful," from menda "fault, defect, carelessness in writing," from PIE root *mend- "physical defect, fault" (see amend (v.)). The sense evolution of Latin mendax was influenced by mentiri "to speak falsely, lie, deceive." Related: Mendaciously; mendaciousness.
mendacity (n.): "tendency to lie," 1640s, from Middle French mendacité and directly from Late Latin mendacitas "falsehood, mendacity," from Latin mendax "lying; a liar" (see mendacious).
mendelevium (n.): 1955, Modern Latin, in honor of Russian chemist Dmitri Ivanovich Mendeleev (1834-1907). With metallic element ending -ium.
Mendelism (n.): 1903, in reference to the work of Gregor Johann Mendel (1822-1884), Austrian biologist who enunciated the laws of heredity. Related: Mendelian.
mender (n.): late 14c., agent noun from mend (v.).
mendicancy (n.): "state or condition of beggary," 1790, from mendicant + -cy. Also in this sense was mendicity (c. 1400), from Old French mendicité "begging," from Latin mendicitatem (nominative mendicitas) "beggary, mendicity."
mendicant (adj.): late 14c., from Latin mendicantem (nominative mendicans) present participle of mendicare "to beg, ask alms," from mendicus "beggar," originally "cripple" (connection via cripples who must beg), from menda "fault, physical defect" (see mendacious). As an adjective from 1540s. Also in Middle English was mendinant (mid-14c.), from Old French mendinant, present participle of mendiner "to beg," from the same Latin source.
mendicant (n.): "a beggar," mid-15c., from mendicant (adj.) or from Latin mendicantem (nominative mendicans), noun use of present participle of mendicare.
Menelaus: king of Sparta, husband of Helen, brother of Agamemnon, Latinized form of Greek Menelaos, literally "restraining the people," from menein "to stay, abide, remain" + laos "people" (see lay (adj.)).
menfolk (n.): also men-folk "the male sex, men generally," 1802, from men + folk (n.).
menhaden (n.): kind of herring, 1792, from Algonquian (probably Narragansett) munnawhateaug (noted from 1643), literally "they fertilize," because the abundant little fishes were used by the Indians as fertilizer.
menhir (n.): "upright monumental stone," 1834, literally "long stone," from French menhir (19c.), from Breton men "stone" + hir "long," from PIE *se-ro-, from root *se- "long, late" (see soiree). Cognate with Welsh maen hir, Cornish medn hir.
menial (adj.): late 14c., "pertaining to a household," from Anglo-French meignial, from Old French mesnie "household," earlier mesnede, from Vulgar Latin *mansionata, from Latin mansionem "dwelling" (see mansion). Sense of "lowly, humble, suited to a servant" is recorded by 1670s.
menial (n.): "domestic servant," late 14c., meynyal; see menial (adj.).
meningeal (adj.): 1829, from Modern Latin meningeus, from meninx "membrane of the brain" (1610s; see meningitis) + -al (1).
meninges (n.): plural, 1610s, "the three membranes enveloping the brain and spinal cord," from Middle French meninges (1530s) or directly from medical Latin, plural of meninx, from Greek meninx (see meningitis).
meningitis (n.): "inflammation of the meninges," 1825, coined from Modern Latin meninga, from Greek meninx (genitive meningos) "membrane," in medical Latin especially that of the brain (see member) + -itis "inflammation." Related: Meningitic.
meniscus (n.): "crescent-shaped body," 1690s in reference to lenses, c. 1812 in reference to liquid surfaces, Modern Latin meniscus, from Greek meniskos "lunar crescent," diminutive of mene "moon" (see moon (n.)). Related: Meniscoid.
Mennonite (n.): member of an Anabaptist sect, 1560s, from name of Menno Simons (1492-1559), founder of the sect in Friesland, + -ite (1). As an adjective by 1727. Alternative form Mennonist (n.) attested from 1640s.
Menominee: also Menomini, Algonquian people of Wisconsin, from Ojibwa (Algonquian) Manoominii, literally "wild rice people," from manoomin "wild rice." Not their name for themselves.
menopausal (adj.): 1879, from menopause + -al (1).