pileus

n.; pl. Pilei [ L., a felt cap. ] 1. (Rom. Antiq.) A kind of skull cap of felt. [ 1913 Webster ]

2. (Bot.) The expanded upper portion of many of the fungi. See Mushroom. [ 1913 Webster ]

3. (Zool.) The top of the head of a bird, from the bill to the nape. [ 1913 Webster ]