magic mushroomEnglishOxford Dictionary of Englishmagic mushroom /ˌmadʒɪk ˈmʌʃruːm , ˌmadʒɪk ˈmʌʃrʊm / ▸ noun informal a toadstool with hallucinogenic properties, especially the liberty cap and its relatives. Genus Psilocybe, family Strophariaceae, class Hymenomycetes: several species.