Apse and Aperture

Apse noun - A domed or vaulted recess or projection on a building especially the east end of a church; usually contains the altar.

Aperture and apse are semantically related. In some cases you can use "Aperture" instead a noun "Apse".

Aperture noun - A place in a surface allowing passage into or through a thing.

Apse and aperture are semantically related. Sometimes you can use "Apse" instead a noun "Aperture".