calotte

noun4

1. •
   A skullcap worn by Roman Catholic priests.
2. •
   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.
3. •
   The upper (superior) or lower (inferior) half of the globe of the eye.
4. •
   (no longer used) The vertical central area of the crown of a bird's head.