Webster's Revised Unabridged Dictionary · 1913

(Botany) A genus of poisonous fungi of the family Agaricacea, characterized by having a volva, an annulus, and white spores. The species resemble edible mushrooms, and are frequently mistaken for them. Amanita muscaria, syn. Agaricus muscarius, is the fly amanita, or fly agaric; and Agaricus phalloides is the death cup (or death cap).