from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Architecture An apse.
  • n. Astronomy The point of greatest or least distance of the orbit of a celestial body from a center of attraction.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A recess or projection, with a dome or vault, at the east end of a church; an apse.
  • n. 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

from the GNU version of the Collaborative International Dictionary of English

  • n. 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.
  • n. In a curve referred to polar coördinates, any point for which the radius vector is a maximum or minimum.
  • n. Same as Apse.

from The Century Dictionary and Cyclopedia

  • n. In astronomy, a point in the eccentric orbit of a planet in which it is either furthest from or nearest to the body about which it revolves.
  • n. In architecture, same as apse.
  • n. A reliquary or case in which the relies of saints are kept, especially one of a form imitating the curves of a dome or vault.
  • n. Sometimes written absis.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

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


Late Latin, from Latin, arch, vault, from Greek hapsis, from haptein, to fasten.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Via Latin apsis, from Ancient Greek ἁψίς (hapsis, "arch, vault"). See also apse. (Wiktionary)



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  • "... in astronomy, is applied to either of the two points in the orbits of planets, where they are at their greatest and least distance from the sun or earth. The higher apsis is that which is nearest the sun or earth, and is synonimous (sic) with perihelion and perigee; the lower apsis is that which is farthest from the sun or earth; and corresponds to aphelion, or apogee. The line which joins these two points is called the line of the apses, or apsides."
    Falconer's New Universal Dictionary of the Marine (1816), 19–20

    October 14, 2008