Antrum and Apse

Antrum noun - A natural cavity or hollow in a bone.

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

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

Antrum and apse are semantically related. Sometimes you can use "Antrum" instead a noun "Apse".