Source : Webster's Revised Unabridged Dictionary (1913)

Dog Star \Dog" Star`\
   Sirius, a star of the constellation Canis Major, or the
   Greater Dog, and the brightest star in the heavens; -- called
   also {Canicula}, and, in astronomical charts, {[alpha] Canis
   Majoris}. See {Dog days}.

Source : WordNet®

Canicula
     n : the brightest star in the sky; in Canis Major [syn: {Sirius},
          {Dog Star}, {Sothis}]