From Longman Dictionary of Contemporary Englishmushroom cloudˈmushroom ˌcloud noun [countable usually singular] PMWHPa large cloud shaped like a mushroom, which is caused by a nuclear explosion
Examples from the Corpus
mushroom cloud• Sandro Botticelli s chart of hell is like a mushroom cloud or a child s spinning top.• Some amyl too, which blew Jed's head up like a mushroom cloud.• But atomic power to my generation always means that mushroom cloud.• Dust is raised by near-surface bursts and lifted to high altitudes by the mushroom cloud. 