I. ˈməsh-ˌrüm, -ˌru̇m; chiefly Northern & Midland -ˌrün; dialect ˈmə-shə-ˌrüm, -ˌru̇m, -ˌrün noun
Etymology: Middle English musheron, from Anglo-French musherum, musseron, from Late Latin mussirion-, mussirio
Date: 15th century
1.
a. : an enlarged complex aboveground fleshy fruiting body of a fungus (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
II. intransitive verb
Date: 1893
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