genus Agaricus ge·nu·sa·garicus uncommon noun 1. type genus of Agaricaceae; gill fungi having brown spores and including several edible species SynonymsAgaricusgenus Agaricus Related words Broader terms fungus genus Parts Agaricaceae Part of horse mushroommeadow mushroom WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.