(architecture) An apse.
(astronomy) The point of greatest or least distance of the orbit of a celestial body from the center of mass of the system.
That point in the elliptical orbit of the moon, a planet, etc. nearest to (lower apsis), or that farthest from (higher apsis), the gravitational focus point.
In the path of an orbiting body, either of the two points at which it is closest to or farthest away from the body it is orbiting.
line of apsides
- a line joining the lower and higher apsides, forming the major axis of the orbit