apsis
/ˈæpsɪs/ noun
- noun (architecture) A recess or projection, with a dome or vault, at the east end of a church.
- noun (astronomy) 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.
Synonyms
Etymology
From Latin apsis, hapsis, from Ancient Greek ἁψίς (hapsís, “arch, vault”). See also apse.
Webster’s 1913
- noun 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.
- noun In a curve referred to polar coördinates, any point for which the radius vector is a maximum or minimum.
Sources: Wiktionary · Webster’s 1913 — from the Wiktionary entry “apsis”, CC BY-SA 4.0. Details