I. ˈməˌshrü]m, -ru̇], chiefly dial ]n\ noun
( -s )
Usage: often attributive
Etymology: Middle English musseroun, muscheron, from Middle French mousseron, from Old French meisseron, from Late Latin mussirion-, mussirio
1.
a.
(1) : any of various enlarged complex aerial fleshy fruiting bodies of fungi (as most members of the class Basidiomycetes) that are technically sporophores, arise from an underground mycelium, and consist typically of a stem bearing a flattened pileus with spores developing in the folds or pores of a hymenium on its undersurface
(2) : such a fruiting body that is edible ; especially : meadow mushroom — compare toadstool
b. : fungus 1
2. archaic : upstart 1
3. slang : umbrella
4. : a woman's low-crowned hat with a convex brim
5.
a. : mushroom anchor
b. : the head of a mushroom anchor without the shank
6. : a metal traffic guide about 18 inches in diameter fixed in the pavement surface at an intersection
7. : a bullet with a soft or hollow point that flattens on impact
8. : an obturator for a cannon
9. : a lateral and radial extension of reinforcing rods into the slab at the top of each column in a system of reinforced-concrete construction permitting the weight of the floors to be borne by the columns rather than by external walls
10. : a spreading cloud (as of smoke or debris)
mushroom of exploding five-inch shells — K.M.Dodson
radioactive mushroom from an atom-bomb explosion
the stem of the mushroom caused by the intense heat sucking up … debris — E.P.Boland
11. : beaver 6
II. verb
( -ed/-ing/-s )
intransitive verb
1. : to spring up suddenly or multiply rapidly
towns … mushroomed about factories near water power — R.H.Brown
accidents mushroomed so prodigiously … that it was evident some basic factor had been overlooked — Stanley Frank
— often used with up
stools and benches decorated with her handiwork had mushroomed up all over the house — Virginia D. Dawson & Betty D. Wilson
2.
a. : to flatten at the end due to impact — used especially of a bullet
bullets mushroomed well, so the animal did not go far — W.Z.Bradley
b. : to puff out or spread
the cloud of radioactive ash … mushrooms from the bomb — Newsweek
the homely aroma … came mushrooming over us — William Sansom
especially : to well up and spread out laterally from a central source
the fire was mushrooming under the ceiling when fire fighters … arrived — Springfield (Massachusetts) Union
c. : to become enlarged or extended : expand , grow
appetites mushroom on the trail — Joyce R. Muench
from a sleepy little rural community … it has mushroomed into a fast-growing center — Martha Alexander
the vast mushrooming of air travel — Fortune
d. : explode
an enemy plane … mushrooms in your gunsight — R.L.Scott
3. : to gather mushrooms
transitive verb
1. : to cause to spread or flatten out
hammering can … mushroom the end of the handle — H.D.Burghardt & Aaron Axelrod
2. : to cause to extend or multiply suddenly or rapidly : expand
a city swollen with a mushroomed population — Earl Brown
mushroomed his interests over three quarters of the U.S. — Time