apsis

  1. Noun.  (architecture) A recess or projection, with a dome or vault, at the east end of a church; an apse.
  2. Noun.  (astronomy) 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.

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This entry was last updated on RefTopia from its source on 3/20/2012.