- An edible fungus (Agaricus campestris), having a white
stalk which bears a convex or oven flattish expanded portion called the
pileus. This is whitish and silky or somewhat scaly above, and bears on
the under side radiating gills which are at first flesh-colored, but
gradually become brown. The plant grows in rich pastures and is
proverbial for rapidity of growth and shortness of duration. It has a
pleasant smell, and is largely used as food. It is also cultivated from
spawn. - Any large fungus, especially one of the genus Agaricus; a
toadstool. Several species are edible; but many are very poisonous. - One who rises suddenly from a low condition in life; an
upstart. - Of or pertaining to mushrooms; as, mushroom catchup. - Resembling mushrooms in rapidity of growth and shortness
of duration; short-lived; ephemerial; as, mushroom cities.