Mushroom

n. [Fr. mousseron, from mousse, moss, because it grows in it. See Moss.] 1. (Bot.) One of a large class of cryptogamic plants of the natural order of Fungi. The name is sometimes popularly restricted to such species as are used as food. See FUNGUS.

The mushrooms are cellular plants, having generally a more or less rounded thallus supported upon a stalk, and having spores or seeds upon the under surface or gills. They are very numerous, being found in all parts of the world, and are usually of very rapid growth, often springing up and coming to maturity in a single day. Many species are used for food in different parts of the world, while other species are poisonous. Baird.

2Sense 2. One who rises suddenly from a low condition in life; an upstart. Bacon.

Mushroom spawn, the seed of the mushroom, sold in the mass by gardeners. Simmonds.