from
The Collaborative International Dictionary of English v.0.48
Mushroom \Mush"room\, a.
1. Of or pertaining to mushrooms; as, mushroom catchup.
[1913 Webster]
2. Resembling mushrooms in rapidity of growth and shortness
of duration; short-lived; ephemerial; as, mushroom cities.
[1913 Webster]
{Mushroom anchor}, an anchor shaped like a mushroom, capable
of grasping the ground in whatever way it falls.
{Mushroom coral} (Zool.), any coral of the genus {Fungia}.
See {Fungia}.
{Mushroom spawn} (Bot.), the mycelium, or primary filamentous
growth, of the mushroom; also, cakes of earth and manure
containing this growth, which are used for propagation of
the mushroom.
{mushroom cloud}, a cloud of smoke rising and then spreading
laterally to take on the shape of a mushroom -- caused by
large fires or explosions, esp. nuclear explosions.
[1913 Webster +PJC]