Source : Webster's Revised Unabridged Dictionary (1913)

Centaur \Cen"taur\, n. [L. centaurus, Gr. ?.]
   1. (Class. Myth.) A fabulous being, represented as half man
      and half horse.

   2. (Astron.) A constellation in the southern heavens between
      Hydra and the Southern Cross.

Source : WordNet®

centaur
     n 1: (classical mythology) a mythical being that is half man and
          half horse
     2: a conspicuous constellation in the southern hemisphere near
        the Southern Cross [syn: {Centaurus}, {The Centaur}]