Noun apsis has 1 sense

1. apse, apsis - a domed or vaulted recess or projection on a building especially the east end of a church; usually contains the altar
   --₁ is a kind of recess, niche
   --₁ is a part of church, church building
   --₁ has particulars: tribune
   

Apsis

Noun - Astronomy: The point in the orbit of a celestial body where it is furthest or closest to its primary.

Example Sentence: The Moon reaches its apsis when it comes closest to Earth.

Noun - Architecture: The semi-circular or pointed end of a building, usually a church, that contains the altar.

Example Sentence: The stained glass window behind the apsis depicted a beautiful religious scene.

Popular Usage: In astronomy, the apsis is often associated with the ellipses of planetary or satellite orbits.

Local Usage: The apsis of the town's oldest church is an iconic architectural element of our community.

Related Products: Celestial Body Books, Architecture Books