semidome
/ˈsɛmiˌdoʊm/
noun
- A half-dome, especially one that forms part of a building or structure, such as an apse or niche.
- The semidome of the chapel was decorated with colorful mosaics.
- The ancient church had a beautiful semidome above the altar.
- The architect designed a semidome to cover the entrance of the museum.