Pronunciation (UK) (US) IPA (key): /ˈmʌʃˌruːm/ or /ˈmʌʃˌrʊm/ Audio (US)(file) Hyphenation: mush‧room Noun Singular mushroom Plural mushrooms (countable) A mushroom is a fungus that grows on soil or on dying wood. While in the forest, make sure to look on dead trees for mushrooms!Wikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads