Apse
Part of speech: noun
Definition: A semicircular projection from a building, especially the rounded east end of a church that contains the altar. The nearest and furthest points to the centre of gravitational attraction for a body in orbit. More usually called an apsis. In some local dialects and in archaic usage, an aspen tree.
Apsis
Part of speech: noun
Definition: A recess or projection, with a dome or vault, at the east end of a church; an apse.Either of the points in the elliptical orbit of a planet or comet where it is closest or furthest from the sun; perihelion or aphelion; an apside