mushroom (v.) Look up mushroom at Dictionary.com
"expand or increase rapidly," 1741, from mushroom (n.). Related: Mushroomed; mushrooming.
mushy (adj.) Look up mushy at Dictionary.com
"soft, pulpy, 1839; "sentimental," 1870; from mush (n.) + -y (2). Mush (n.) in a transferred sense of "sentimentality" is attested from 1908.
music (n.) Look up music at Dictionary.com
mid-13c., musike, from Old French musique (12c.) and directly from Latin musica "the art of music," also including poetry (also source of Spanish musica, Italian musica, Old High German mosica, German Musik, Dutch muziek, Danish musik), from Greek mousike (techne) "(art) of the Muses," from fem. of mousikos "pertaining to the Muses," from Mousa "Muse" (see muse (n.)). Modern spelling from 1630s. In classical Greece, any art in which the Muses presided, but especially music and lyric poetry.

The use of letters to denote music pitch probably is at least as old as ancient Greece, as their numbering system was ill-suited to the job. Natural scales begin at C (not A) because in ancient times the minor mode was more often used than the major one, and the natural minor scale begins at A.

Music box is from 1773, originally "barrel organ;" music hall is from 1842, especially "hall licensed for musical entertainment" (1857). To face the music "accept the consequences" is from 1850; the exact image is uncertain, one theory ties it to stage performers, another to cavalry horses having to be taught to stay calm while the regimental band plays. To make (beautiful) music with someone "have sexual intercourse" is from 1967.
musical (adj.) Look up musical at Dictionary.com
early 15c., "pertaining to music; tuneful, harmonious; adept at making music," from Middle French musical (14c.) and directly from Medieval Latin musicalis, from Latin musica (see music). Musical box is from 1829. Children's game musical chairs is attested from 1877, hence use of musical as a modifier meaning "changing rapidly from one to another possessor" (1924). Related: Musically.
musical (n.) Look up musical at Dictionary.com
"theatrical piece in which music figures prominently," 1937, from musical (adj.) in musical play. Earlier as a noun it meant "musical instrument" (c.1500), "musical performance" (1570s); "musical party" (1823, a sense now in musicale).
musicale (n.) Look up musicale at Dictionary.com
"musical party," 1872, from French musicale, short for soirée musicale "musical evening (party);" see musical (adj.).
musicality (n.) Look up musicality at Dictionary.com
1812, from musical (adj.) + -ity.
musician (n.) Look up musician at Dictionary.com
late 14c., "one skilled in music," from Old French musicien (14c.), or a native formation from music + -ian. Sense of "professional musical performer" first recorded mid-15c.
musicianship (n.) Look up musicianship at Dictionary.com
1828, from musician + -ship.
musico- Look up musico- at Dictionary.com
word-forming element from comb. form of Latin musicus (see music).
musicology (n.) Look up musicology at Dictionary.com
"the study of the science of music," 1909, from music + -ology. Related: Musicological; musicologist.
musing (n.) Look up musing at Dictionary.com
late 14c., "complaint," verbal noun from muse (v.). Meaning "pondering" is from mid-15c. Related: Musingly; musings.
musk (n.) Look up musk at Dictionary.com
late 14c., from Old French musc (13c.) and directly from Late Latin muscus, from Late Greek moskhos, from Persian mushk, from Sanskrit muska-s "testicle," from mus "mouse" (so called, presumably, for resemblance; see muscle). The deer gland was thought to resemble a scrotum. German has moschos, from a Medieval Latin form of the Late Greek word. Spanish has almizcle, from Arabic al misk "the musk," from Persian. Applied to various plants and animals of similar smell (such as musk-ox, 1744).
muskeg (n.) Look up muskeg at Dictionary.com
kind of moss bog, 1865, from a Cree Indian word.
muskellunge (n.) Look up muskellunge at Dictionary.com
"large North American pike," 1789, from Algonquian (Ojibwa) maashkinoozhe; the second element kinoozhe "pike;" the first either mac "great," maazh- "similar to," or maazh- "ugly." Altered by French folk etymology as masque allongé "long mask." Called muskie for short (1894).
musket (n.) Look up musket at Dictionary.com
"firearm for infantry" (later replaced by the rifle), 1580s, from Middle French mousquette, also the name of a kind of sparrow-hawk, diminutive of mosca "a fly," from Latin musca (see midge). The hawk so called either for its size or because it looks speckled when in flight. Early firearms often were given names of beasts (compare dragoon), and the equivalent word in Italian was used to mean "an arrow for a crossbow." The French word was borrowed earlier into English (early 15c.) in its literal sense of "sparrow-hawk."
musketeer (n.) Look up musketeer at Dictionary.com
"soldier armed with a musket," 1580s, from musket + -eer, or else from French mousquetaire, from mousquette (see musket).
musketry (n.) Look up musketry at Dictionary.com
1640s, from French mousqueterie, from mousquet "musket" (see musket), on analogy of Italian moschetteria.
Muskoegan Look up Muskoegan at Dictionary.com
North American Indian language family, 1891, from Creek maskoki.
muskrat (n.) Look up muskrat at Dictionary.com
also musk-rat, 1610s, alteration (by association with musk and rat) of musquash, from Algonquian (probably Powhatan) muscascus, literally "it is red," so called for its colorings. From cognate Abenaki muskwessu comes variant form musquash (1620s).
musky (adj.) Look up musky at Dictionary.com
c.1600, from musk + -y (2). Related: Muskiness.
musky (n.) Look up musky at Dictionary.com
late 19c., short for muskrat or muskellunge. Also muskie.
Muslim Look up Muslim at Dictionary.com
1610s (n.), 1777 (adj.), from Arabic muslim "one who submits" (to the faith), from root of aslama "he resigned." Related to Islam.
muslin (n.) Look up muslin at Dictionary.com
c.1600, "delicately woven cotton fabric," from French mousseline (17c.), from Italian mussolina, from Mussolo, Italian name of Mosul, city in northern Mesopotamia (modern Iraq) where muslin was made. Like many fabric names, it has changed meaning over the years, in this case from luxurious to commonplace. In 13c. French, mosulin meant "cloth of silk and gold." The meaning "everyday cotton fabric for shirts, bedding, etc." is first attested 1872 in American English.
muss (v.) Look up muss at Dictionary.com
"to make untidy," 1837, probably a variant of mess in its sense of "disorder." Earlier (1830) as a noun meaning "disturbance." Related: Mussed; mussing.
mussel (n.) Look up mussel at Dictionary.com
Old English muscle, musscel "shellfish, mussel," from Late Latin muscula (source of Old French musle, Modern French moule, Middle Dutch mosscele, Dutch mossel, Old High German muscula, German Muschel), from Latin musculus "mussel," literally "little mouse," also "muscle;" like muscle, derived from mus "mouse" on the perceived similarity of size and shape. The modern spelling, distinguishing the word from muscle, first recorded c.1600, not fully established until 1870s.
Mussulman (n.) Look up Mussulman at Dictionary.com
"a Muslim," 1560s, from Turkish musulman, from Persian musulman (adj.), from Arabic muslim (see Muslim) + adjective suffix -an.
mussy (adj.) Look up mussy at Dictionary.com
"rumpled," 1859, from muss + -y (2). Related: Mussiness.
must (v.) Look up must at Dictionary.com
Old English moste, past tense of motan "have to, be able to," from Proto-Germanic *mot- "ability, leisure (to do something)" (cognates: Old Saxon motan "to be obliged to, have to," Old Frisian mota, Middle Low German moten, Dutch moeten, German müssen "to be obliged to," Gothic gamotan "to have room to, to be able to"), perhaps from PIE root *med- "to measure, to take appropriate measures" (see medical (adj.)). Used as present tense from c.1300, from the custom of using past subjunctive as a moderate or polite form of the present.
must (n.1) Look up must at Dictionary.com
"new wine," Old English must, from Latin mustum (also source of Old High German, German most, Old French moust, Modern French moût, Spanish, Italian mosto), short for vinum mustum "fresh wine," neuter of mustus "fresh, new, newborn," perhaps literally "wet," and from PIE *mus-to-, from root *meus- "damp" (see moss).
must (n.2) Look up must at Dictionary.com
"mold," c.1600, perhaps a back-formation of musty (q.v.).
must (n.3) Look up must at Dictionary.com
"male elephant frenzy," 1871, from Urdu mast "intoxicated, in rut," from Persian mast, literally "intoxicated," related to Sanskrit matta- "drunk, intoxicated," past participle of madati "boils, bubbles, gets drunk," from PIE root *mad- "wet, moist" (see mast (n.2)).
must (n.4) Look up must at Dictionary.com
"that which has to be done, seen, or experienced," 1892, from must (v.). As an adjective, "obligatory, indispensable," by 1912, from the noun; must-read is from 1959.
mustache (n.) Look up mustache at Dictionary.com
1580s, from French moustache (15c.), from Italian mostaccio, from Medieval Greek moustakion, diminutive of Doric mystax (genitive mystakos) "upper lip, mustache," related to mastax "jaws, mouth," literally "that with which one chews," from PIE root *mendh- "to chew" (see mandible).

Borrowed earlier (1550s) as mostacchi, from the Italian word or its Spanish derivative mostacho. The plural form of this, mustachios, lingers in English. Slang shortening stache attested from 1985. Dutch slang has a useful noun, de befborstel, to refer to the mustache specifically as a tool for stimulating the clitoris; probably from beffen "to stimulate the clitoris with the tongue."
mustachioed (adj.) Look up mustachioed at Dictionary.com
1817, from mustachio (1550s), from Spanish mostacho and directly from Italian mostaccio (see mustache). The noun was superseded by mustache, but the adjective has endured.
mustang (n.) Look up mustang at Dictionary.com
"small, half-wild horse of the American prairie," 1808, from Mexican Spanish mestengo "animal that strays" (16c.), from Spanish mestengo "wild, stray, ownerless," literally "belonging to the mesta," an association of cattle ranchers who divided stray or unclaimed animals that got "mixed" with the herds, from Latin mixta "mixed," fem. past participle of miscere "to mix" (see mix (v.)).

Said to be influenced by the Spanish word mostrenco "straying, wild," which is probably from mostrar, from Latin monstrare "to show."
mustard (n.) Look up mustard at Dictionary.com
late 13c. (late 12c. as a surname), from Old French mostarde "mustard, mustard plant" (Modern French moutarde), from moust "must," from Latin mustum "new wine" (see must (n.1)); so called because it was originally prepared by adding must to the ground seeds of the plant to make a paste. As a color name, it is attested from 1848.

Mustard gas, World War I poison (first used by the Germans at Ypres, 1917), so called for its color and smell and burning effect on eyes and lungs; chemical name is dichlordiethyl sulfide, it contains no mustard, and is an atomized liquid, not a gas. To cut the mustard (1907, usually in negative) is probably from slang mustard "genuine article, best thing" (1903) on notion of "that which enhances flavor."
I'm not headlined in the bills, but I'm the mustard in the salad dressing just the same. [O.Henry, "Cabbages and Kings," 1904]
mustee (n.) Look up mustee at Dictionary.com
"octoroon, offspring of a white and a quadroon," also "half-caste," 1690s, a corruption of Spanish mestizo (q.v.).
mustelid (n.) Look up mustelid at Dictionary.com
1910, from Modern Latin Mustelidae, taken as a genus name by Linnaeus (1758), from Latin mustela "weasel," possibly related to mus "mouse" (see mouse (n.)). Tucker tentatively suggests *mus-ters-la "mouse harrier" and Klein notes that the weasel was identified in antiquity as "the catcher of mice."
musteline (adj.) Look up musteline at Dictionary.com
"weasel-like; pertaining to weasels," 1650s, from Latin mustela (see mustelid) + -ine (1).
muster (v.) Look up muster at Dictionary.com
c.1300, "to display, reveal, appear," from Old French mostrer "appear, show, reveal," also in a military sense (10c., Modern French montrer), from Latin monstrare "to show," from monstrum "omen, sign" (see monster). Meaning "to collect, assemble" is early 15c.; figurative use (of qualities, etc.) is from 1580s. To muster out "gather to be discharged from military service" is 1834, American English. To muster up in the figurative and transferred sense of "gather, summon, marshal" is from 1620s. Related: Mustered; mustering.
muster (n.) Look up muster at Dictionary.com
late 14c., "action of showing, manifestation," from Old French mostre "illustration, proof; examination, inspection" (13c., Modern French montre), literally "that which is shown," from mostrer (see muster (v.)). Meaning "act of gathering troops" is from c.1400. To pass musters (1570s) originally meant "to undergo military review without censure."
mustn't Look up mustn't at Dictionary.com
by mid-18c., contraction of must not; see must (v).
musty (adj.) Look up musty at Dictionary.com
1520s, perhaps a variant of moisty "moist, damp" (see moist). Related: Mustiness.
mutability (n.) Look up mutability at Dictionary.com
late 14c., "tendency to change, inconstancy," from Middle French mutabilité, from Latin mutabilitas, from mutabilis (see mutable).
mutable (adj.) Look up mutable at Dictionary.com
late 14c., "liable to change," from Latin mutabilis "changeable," from mutare "to change," from PIE root *mei- (1) "to change, go, move" (cognates: Sanskrit methati "changes, alternates, joins, meets;" Avestan mitho "perverted, false;" Hittite mutai- "be changed into;" Latin meare "to go, pass," migrare "to move from one place to another;" Old Church Slavonic mite "alternately;" Czech mijim "to go by, pass by," Polish mijać "avoid;" Gothic maidjan "to change"); with derivatives referring to the exchange of goods and services as regulated by custom or law (compare Latin mutuus "done in exchange," munus "service performed for the community, duty, work").
mutagen (n.) Look up mutagen at Dictionary.com
1946, from mutation + -gen "thing that produces." Related: Mutagenic; mutagenesis; mutagenize.
mutant (n.) Look up mutant at Dictionary.com
1901, in the biological sense, from Latin mutantem (nominative mutans) "changing," present participle of mutare "to change" (see mutable). In the science fiction sense, it is attested from 1954. As an adjective from 1903.
mutate (v.) Look up mutate at Dictionary.com
"to change state or condition," 1818, back-formation from mutation. In genetic sense, 1913, from Latin mutatus, past participle of mutare "to change" (see mutable). Related: Mutated; mutating.
mutation (n.) Look up mutation at Dictionary.com
late 14c., "action of changing," from Old French mutacion (13c.), and directly from Latin mutationem (nominative mutatio) "a changing, alteration, a turn for the worse," noun of action from past participle stem of mutare "to change" (see mutable). Genetic sense is from 1894.