cham·pi·gnon \shamˈpinyən, -pē- also ch-; F shäⁿpēnʸōⁿ\noun (-s) Etymology: Middle French, alteration of champigneul, from champagne level country — more at champaign 1.obsolete: fungus 2.: an edible fungus; especially: the common meadow mushroom 3.: a fairy ring (Marasmius oreades)