apsis Meaning, Definition & Usage

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

L. apsis, absis, Gr. , , a tying, fastening, the hoop of a wheel, the wheel, a bow, arch, vault, fr. to fasten.

plural Apsides

(Astron.) One of the two points of an orbit, as of a planet or satellite, which are at the greatest and least distance from the central body, corresponding to the aphelion and perihelion of a planet, or to the apogee and perigee of the moon. The more distant is called the higher apsis; the other, the lower apsis; and the line joining them, the line of apsides.
(Math.) In a curve referred to polar coördinates, any point for which the radius vector is a maximum or minimum.
(Arch.) Same as Apse.