calotte

A skullcap worn by Roman Catholic priests.

(anatomy) The upper (superior) or lower (inferior) half of the globe of the eye.

(architecture) A round cavity or depression, in the form of a cup or cap, lathed and plastered; used to diminish the rise or elevation of a moderate chapel, alcove, etc. which would otherwise be too high for other pieces of the apartment.

(archaic) The vertical central area of the crown of a bird's head.