Pileus \Pi"le*us\, n.; pl. {Pilei}. [L., a felt cap.] 1. (Rom. Antiq.) A kind of skull cap of felt. 2. (Bot.) The expanded upper portion of many of the fungi. See {Mushroom}. 3. (Zo["o]l.) The top of the head of a bird, from the bill to the nape.
pileus n : a fruiting structure resembling an umbrella that forms the top of a stalked fleshy fungus such as a mushroom [syn: {cap}] [also: {pilei} (pl)] pilei See {pileus}