Source : Webster's Revised Unabridged Dictionary (1913)

Polestar \Pole"star`\, n.
   1. Polaris, or the north star. See {North star}, under
      {North}.

   2. A guide or director.

Source : WordNet®

polestar
     n : the brightest star in Ursa Minor; at the end of the handle
         of the little dipper; the northern axis of the earth
         points toward it [syn: {Polaris}, {North Star}, {pole
         star}, {polar star}]