Source : Webster's Revised Unabridged Dictionary (1913)

Caaba \Ca*a"ba\ (k[.a]*[=a]"b[.a]), n. [Ar. ka'bah, lit., a
   square building, fr. ka'b cube.]
   The small and nearly cubical stone building, toward which all
   Mohammedans must pray. [Written also {kaaba}.]

   Note: The Caaba is situated in Mecca, a city of Arabia, and
         contains a famous black stone said to have been brought
         from heaven. Before the time of Mohammed, the Caaba was
         an idolatrous temple, but it has since been the chief
         sanctuary and object of pilgrimage of the Mohammedan
         world.

Source : WordNet®

Caaba
     n : (Islam) a black stone building in Mecca that is shaped like
         a cube and that is the most sacred Muslim pilgrim shrine;
         believed to have been given by Gabriel to Abraham;
         Muslims turn in its direction when praying [syn: {Kaaba}]