Noun

1. Common name for an edible agaric (contrasting with the inedible toadstool)
2. Mushrooms and related fleshy fungi (including toadstools, puffballs, morels, coral fungi, etc.)
3. Any of various fleshy fungi of the subdivision basidiomycota consisting of a cap at the end of a stem arising from an underground mycelium
4. A large cloud of rubble and dust shaped like a mushroom and rising into the sky after an explosion (especially of a nuclear bomb)
5. Fleshy body of any of numerous edible fungi

Verb

1. Pick or gather mushrooms
2. Grow and spread fast