mushroom

From Middle English muscheron, musseron, from Anglo-Norman musherum, moscheron, from Old French moisseron, of obscure origin: probably derived from Old French mosse, moise (“moss”), as the use first applied to a type of fungus which grows in moss, from Frankish *mosa (“moss”) or Old Dutch mosa (“moss”), akin to Old High German mos (“moss, bog”), Old High German mios (“moss, mire”), Old English mēos (“moss”), Old English mōs (“bog, marsh”), Old Norse mosi (“moss”), Old Norse myrr (“bog, mire”), from Proto-Germanic *musą, *musô, *miuziz (“mosses, bog”), from Proto-Indo-European *mews- (“mosses, mold, mildew”). Displaced native Old English swamm. More at mire. Alternatively, the Old French may be of pre-Roman origin. See Ancient Greek μύκης (múkēs, “mushroom”).

• (UK, US) IPA^(key): /ˈmʌʃˌɹuːm/, /ˈmʌʃˌɹʊm/

• Audio (US)

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• Rhymes: -ʌʃɹuːm, -ʌʃɹʊm
• Hyphenation: mush‧room

mushroom (plural mushrooms)

1. Any of the fleshy fruiting bodies of fungi typically produced above ground on soil or on their food sources (such as decaying wood).

   Synonyms: (archaic) mushrump, shroom

   Some mushrooms are edible and taste good, while others are poisonous and taste foul.

2. A fungus producing such fruiting bodies.
3. Champignon or Agaricus bisporus, the mushroom species most commonly used in cooking.
4. Any of the mushroom-shaped pegs in bar billiards.
5. (architecture) A concrete column with a thickened portion at the top, used to support a slab.
6. (obsolete, figurative) One who rises suddenly from a low condition in life; an upstart.
   • 1631, Francis [Bacon], “6. Century.”, in Sylua Syluarum: Or A Naturall Historie. In Ten Centuries. […], 3rd edition, London: […] William Rawley; [p]rinted by J[ohn] H[aviland] for William Lee […], OCLC 1044372886:

     upstarts […] call in reproach mushrooms

7. (figurative) Something that grows very quickly or seems to appear suddenly.
8. Ellipsis of mushroom cloud.

• → Japanese: マッシュルーム

“mushroom”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

mushroom (not comparable)

1. Having characteristics like those of a mushroom, for example in shape or appearance, speed of growth, or texture.

   mushroom cloud

mushroom (third-person singular simple present mushrooms, present participle mushrooming, simple past and past participle mushroomed)

1. (intransitive, figurative) To grow quickly to a large size.

   The town’s population mushroomed from 10,000 to 110,000 in five years.

   • 2019 June 1, Oliver Wainwright, “Super-tall, super-skinny, super-expensive: the ‘pencil towers’ of New York’s super-rich”, in Katharine Viner, editor, The Guardian‎, London: Guardian News & Media, ISSN 0261-3077, OCLC 229952407, archived from the original on 5 October 2020:

     The world's population of ultra-high-net-worth individuals, a super-elite with assets of at least $30m, has now mushroomed beyond 250,000 people, all in need of somewhere to store their wealth.

   • 2021 February 10, Thomas L. Friedman, “Cyberspace Plus Trump Almost Killed Our Democracy. Can Europe Save Us?”, in The New York Times‎, ISSN 0362-4331:

     It has its own global news gathering and sharing platforms, like Facebook, YouTube and Twitter. […] In recent years, all these platforms have mushroomed.

2. To gather mushrooms.

   We used to go mushrooming in the forest every weekend.

3. To form the shape of a mushroom.
   • 2001, James E. Duffy, I-Car Professional Automotive Collision Repair (page 173)

     Excessive spot weld time may cause the electrode tips to mushroom, resulting in no focus of current and a weak weld.

   1. (ballistics, of a bullet) To form the shape of a mushroom when striking a soft target.