oyster mushroom noun2 •The mushroom Pleurotus ostreatus, which in the wild grows chiefly on hardwood trees, and is cultivated for food.Oyster Mushrooms always grow on wood—but sometimes above roots or beside stumps, which creates the illusion they're growing from soil, which they're not. — 2009 •Any of several mushrooms of the genus Pleurotus cultivated for food. formsoyster mushrooms
