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[muhsh-room, -roo m] /ˈmʌʃ rum, -rʊm/
any of various fleshy fungi including the toadstools, puffballs, coral fungi, morels, etc.
any of several edible species, especially of the family Agaricaceae, as Agaricus campestris (meadow mushroom or field mushroom) cultivated for food in the U.S.
anything of similar shape or correspondingly rapid growth.
a large, mushroom-shaped cloud of smoke or rubble, formed in the atmosphere as a result of an explosion, especially a nuclear explosion.
of, consisting of, or containing mushrooms:
a mushroom omelet.
resembling a mushroom in shape or form.
of rapid growth and often brief duration:
mushroom towns of the gold-rush days.
verb (used without object)
to spread, grow, or develop quickly.
to gather mushrooms.
to have or assume the shape of a mushroom.
1350-1400; alteration (by folk etymology) of Middle English muscheron, musseroun < Middle French mousseronLate Latin mussiriōn-, stem of mussiriō
Related forms
mushroomlike, adjective
mushroomy, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for mushroom
  • What follows are two recipes for fajitas: one mushroom, one steak.
  • Clean three large mushroom caps, cut in halves crosswise, then in slices.
  • Cook onion and mushroom in butter five minutes, add flour, and pour on gradually oyster liquor and chicken stock.
  • Hen of the woods should not be confused with chicken of the woods, the more appetizing pseudonym of the sulfur shelf mushroom.
  • The frightening-looking mushroom cloud emanating from the cooling tower appeared more hazardous than it actually was.
  • If the economy grinds to a halt, the trade surplus will mushroom.
  • It's the old mushroom philosophy alive and well and stinking.
  • Thus, these adepts no longer experience the oblivion of sleep and this without the mushroom or any other influence.
  • Rather more than half of them disclose the proverbial mushroom cloud, luminous or vapor-borne.
  • They shall be anchored, in four directions, with buried mushroom anchors and heavy chains painted with rubberized epoxy paint.
British Dictionary definitions for mushroom


/ˈmʌʃruːm; -rʊm/
  1. the fleshy spore-producing body of any of various basidiomycetous fungi, typically consisting of a cap (pileus) at the end of a stem arising from an underground mycelium. Some species, such as the field mushroom, are edible Compare pileus, toadstool
  2. (as modifier): mushroom soup
the fungus producing any of these structures
  1. something resembling a mushroom in shape or rapid growth
  2. (as modifier): mushroom expansion
verb (intransitive)
to grow rapidly: demand mushroomed overnight
to assume a mushroom-like shape
to gather mushrooms
Word Origin
C15: from Old French mousseron, from Late Latin mussiriō, of obscure origin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for mushroom

mid-15c., muscheron, musseroun (attested 1327 as a surname, John Mussheron), from Anglo-French musherun, Old French meisseron (11c., Modern French mousseron), perhaps from Late Latin mussirionem (nominative mussirio), though this might as well be borrowed from French. Barnhart says "of uncertain origin." Klein calls it "a word of pre-Latin origin, used in the North of France;" OED says it usually is held to be a derivative of French mousse "moss" (from Germanic), and Weekley agrees, saying it is properly "applied to variety which grows in moss," but Klein says they have "nothing in common." For the final -m Weekley refers to grogram, vellum, venom. Modern spelling is from 1560s.

Used figuratively for something or someone that makes a sudden appearance in full form from 1590s. In reference to the shape of clouds after explosions, etc., it is attested from 1916, though the actual phrase mushroom cloud does not appear until 1955.


"expand or increase rapidly," 1741, from mushroom (n.). Related: Mushroomed; mushrooming.

Online Etymology Dictionary, © 2010 Douglas Harper
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mushroom in Science

Any of various basidiomycete fungi whose mycelium produces a spore-dispersing body (called a basidioma) that usually consists of a stalk topped by a fleshy, often umbrella-shaped cap. Some species of mushrooms are edible, though many are poisonous. The term mushroom is often applied to the stalk and cap alone. See more at basidiomycete.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Slang definitions & phrases for mushroom


  1. A person who is deliberately kept ignorant and misinformed
  2. : The growing contempt for accidental victims is even indicated by the name killers give them: ''mushrooms'' who ''pop up'' in the line of fire (late 1980s+)

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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