Noun | 1. | ![]() fungus genus - includes lichen genera Agaricaceae, family Agaricaceae - large family including many familiar mushrooms oyster agaric, oyster fungus, oyster mushroom, Pleurotus ostreatus - edible agaric with a soft greyish cap growing in shelving masses on dead wood olive-tree agaric, Pleurotus phosphoreus - red luminescent mushroom of Europe |