- 1[intransitive] to rapidly grow or increase in number We expect the market to mushroom in the next two years.
- 2go mushrooming [intransitive] to gather mushrooms in a field or wood
NAmE//ˈmʌʃrum//, NAmE//ˈmʌʃrʊm//Verb Forms present simple I / you / we / they mushroom
,he / she / it mushrooms
,past simple mushroomed
,-ing form mushrooming