apsis

Meanings

1. A recess or projection, with a dome or vault, at the east end of a church.
2. Either of the points in the elliptical orbit of a planet, comet, or moon where it is closest or furthest from the body it orbits; examples are perihelion, aphelion, perigee, and apogee.

Etymology

From Latin apsis, hapsis, from Ancient Greek ἁψίς (hapsís, “arch, vault”). See also apse.