mushroom

1 of 2

noun

mush·​room ˈməsh-ˌrüm 

-ˌru̇m;

 chiefly Northern and Midland US  -ˌrün;

 dialectal  ˈmə-shə-ˌrüm,

-ˌru̇m,

-ˌrün

1

a

: an enlarged complex aboveground fleshy fruiting body of a fungus (such as a basidiomycete) that consists typically of a stem bearing a pileus

especially : one that is edible

b

: fungus

2

: upstart

3

: something resembling a mushroom

mushroom

2 of 2

verb

mushroomed; mushrooming; mushrooms

intransitive verb

1

a

: to well up and spread out laterally from a central source

b

: to become enlarged or extended : grow

2

: to collect wild mushrooms

3

: to spring up suddenly or multiply rapidly

Synonyms

Verb

• increase
• rise
• swell
• accelerate
• wax
• expand
• climb

Examples of mushroom in a Sentence

Noun

cut up some mushrooms for the salad

Verb

Interest in local history is suddenly mushrooming.

Her hobby mushroomed into a thriving business.

He goes mushrooming in the spring every year.

Recent Examples on the Web

Noun

Some mushrooms fluoresce, and that gave Williams an idea about one way deer might be locating mushrooms. —Natalie Krebs, Outdoor Life, 16 Oct. 2025

Gambino’s pizza pies include The Mobster (beef, pork sausage, mushroom, pepperoni, Italian sausage, green pepper, onion, black olives, Canadian bacon, salami and extra cheese), and Taco Pizza (beef, onion, cheese blend, lettuce, refried beans, fresh tomato and taco sauce). —Jenna Thompson, Kansas City Star, 16 Oct. 2025

Verb

Branches of major restaurant and store chains have mushroomed around the center in recent years, and the local mall has become a regional go-to, so much so that Apple massively expanded its store there earlier this year. —Ivana Kottasová, CNN Money, 4 Oct. 2025

Its military and commercial shipbuilding capacity is roughly 230 times larger than that of the United States, and its long-range missile capabilities have mushroomed over the past two decades. —Seth G. Jones, Foreign Affairs, 26 Sep. 2025

Word History

Etymology

Noun

Middle English musheron, from Anglo-French musherum, musseron, from Late Latin mussirion-, mussirio

First Known Use

Noun

15th century, in the meaning defined at sense 1a

Verb

1893, in the meaning defined at sense 1a

Phrases Containing mushroom

• button mushroom
• chaga mushroom
• chicken mushroom
• enokidake mushroom
• enoki mushroom
• enokitake mushroom
• field mushroom
• lion's mane mushroom
• magic mushroom
• meadow mushroom
• mushroom cap
• mushroom cloud
• oyster mushroom
• sacred mushroom
• straw mushroom
• sulfur mushroom

Kids Definition

mushroom

1 of 2 noun

mush·​room ˈməsh-ˌrüm 

-ˌru̇m

1

: a fleshy part of a fungus that bears spores, grows above ground, and consists usually of a stem bearing a flattened cap

especially : one that is edible

2

: fungus sense 1

mushroom

2 of 2 verb

: to appear or develop suddenly or increase rapidly

the population mushroomed

Medical Definition

mushroom

noun

mush·​room ˈməsh-ˌrüm  -ˌru̇m 

1

: an enlarged complex fleshy fruiting body of a fungus (as most basidiomycetes) that arises from an underground mycelium and consists typically of a stem bearing a spore-bearing structure

especially : one that is edible compare toadstool

2

: fungus sense 1