Source : Webster's Revised Unabridged Dictionary (1913)

Constrictor \Con*strict"or\, n.
   1. That which constricts, draws together, or contracts.

   2. (Anat.) A muscle which contracts or closes an orifice, or
      which compresses an organ; a sphincter.

   3. (Zo["o]l.) A serpent that kills its prey by inclosing and
      crushing it with its folds; as, the boa constrictor.

Source : WordNet®

constrictor
     n : any of various large nonvenomous snakes that kill their prey
         by crushing it in its coils