ap·sis /ˈæpsəs/
 近[遠] 日點
 Apse n.; pl. Apses [See Apsis.]
 1. Arch. (a) A projecting part of a building, esp. of a church, having in the plan a polygonal or semicircular termination, and, most often, projecting from the east end. In early churches the Eastern apse was occupied by seats for the bishop and clergy.   Hence: (b) The bishop's seat or throne, in ancient churches.
 2. A reliquary, or case in which the relics of saints were kept.
 Note: ☞ This word is also written apsis and absis.
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 Ap·sis n.; pl. Apsides  See Apse.
 1. 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.
 2. Math. In a curve referred to polar coördinates, any point for which the radius vector is a maximum or minimum.
 3. Arch. Same as Apse.
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 apsis
      n : a domed or vaulted recess or projection on a building
          especially the east end of a church; usually contains the
          altar [syn: apse]
      [also: apsides (pl)]