Pronunciation: (mush'rOOm, -room),[key] —n. 1. any of various fleshy fungi including the toadstools, puffballs, coral fungi, morels, etc.
2. any of several edible species, esp. of the family Agaricaceae, as Agaricus campestris(meadow mushroom or field mushroom), cultivated for food in the U.S.
3. anything of similar shape or correspondingly rapid growth.
4. a large, mushroom-shaped cloud of smoke or rubble, formed in the atmosphere as a result of an explosion, esp. a nuclear explosion.
—adj. 1. of, consisting of, or containing mushrooms: a mushroom omelet. 2. resembling a mushroom in shape or form.
3. of rapid growth and often brief duration: mushroom towns of the gold-rush days.
—v.i. 1. to spread, grow, or develop quickly.
2. to gather mushrooms.
3. to have or assume the shape of a mushroom.