Source : Webster's Revised Unabridged Dictionary (1913)

Apse \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.

Source : WordNet®

apse
     n : a domed or vaulted recess or projection on a building
         especially the east end of a church; usually contains the
         altar [syn: {apsis}]

Source : Free On-Line Dictionary of Computing

APSE
     
        {Ada Programming Support Environment}