Artificial intelligent assistant

apsid

ˈapsid Obs.
  Also 7 abside.
  [a. It. abs{iacu}de; or Fr. abside in Arch., apside in Astron., differentiated adaptations of L. absīd-em or apsīd-em, nom. absis or apsis, also absīda.]
  = apse, apsis.

1670 R. Lassels Voy. Italy II. 103 The picture of our Saviour in the very Tribuno, or Abside [of St. John Lateran]. 1743 Phil. Trans. XLII. 346 A Body approaches from the higher Apsid toward the Centre.

Oxford English Dictionary

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