mushroom

American  

[muhsh-room, -room] / ˈmʌʃ rum, -rʊm /

noun

1. any of various fleshy fungi including the toadstools, puffballs, coral fungi, morels, etc.

2. 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.

3. anything of similar shape or correspondingly rapid growth.

4. a large, mushroom-shaped cloud of smoke or rubble, formed in the atmosphere as a result of an explosion, especially a nuclear explosion.

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adjective

1. of, consisting of, or containing mushrooms.

   a mushroom omelet.

2. resembling a mushroom in shape or form.

3. of rapid growth and often brief duration.

   mushroom towns of the gold-rush days.

verb (used without object)

1. to spread, grow, or develop quickly.

2. to gather mushrooms.

3. to have or assume the shape of a mushroom.

mushroom British  

/ -rʊm, ˈmʌʃruːm /

noun

1. 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

2. the fungus producing any of these structures

3. 1. something resembling a mushroom in shape or rapid growth

   2. ( as modifier )

      mushroom expansion

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verb

1. to grow rapidly

   demand mushroomed overnight

2. to assume a mushroom-like shape

3. to gather mushrooms

mushroom Scientific  

/ mŭsh′ro̅o̅m′ /

1. Any of various fungi that produce a fleshy fruiting body, which usually consists of a stalk topped by an umbrella-shaped cap. Many mushrooms are basidiomycetes. Some species of mushrooms are edible, though many are poisonous. The term mushroom is often applied to the stalk and cap alone.

2. See more at basidiomycete

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Other Word Forms

• mushroomlike adjective
• mushroomy adjective

Etymology

Origin of mushroom

First recorded in 1350–1400; alteration (by folk etymology) of Middle English muscheron, musseroun, from Middle French mousseron, ultimately from Late Latin mussiriōn-, stem of mussiriō

Example Sentences

It’s so bad that Ferrari’s Charles LeClerc says, “This is like the mushroom in Mario Kart.”

From The Wall Street Journal • Mar. 22, 2026

It leans more mushroom than tomato, so the whole thing carries a low, woodsy murmur.

From Salon • Mar. 11, 2026

Paul Stamets and Jeff Chilton began as friends, their collaboration leading to the rise of medicinal mushroom supplements.

From Los Angeles Times • Feb. 24, 2026

The Italian joint with a killer veggie supreme and breadcrumb-and-cheese–stuffed mushroom caps.

From Salon • Feb. 18, 2026

“Why do you keep looking at that mushroom over there?”

From "The Undead Fox of Deadwood Forest" by Aubrey Hartman

Related Words

• boom
• burgeon
• expand
• explode
• flourish
• proliferate
• shoot up