/si(ə)r/
Noun, pl. ceres
1. A waxy structure found in some birds including raptors, owls, skuas, parrots, turkeys and curassows which covers the base of their bill. (wikipedia.org)
2. A waxy, fleshy covering at the base of the upper beak in some birds. (Google Dictionary)
Word origin: From the Latin cera, which means “wax.”