Source : Webster's Revised Unabridged Dictionary (1913)

Retractor \Re*tract"or\, n.
   One who, or that which, retracts. Specifically:
   (a) In breech-loading firearms, a device for withdrawing a
       cartridge shell from the barrel.
   (b) (Surg.) An instrument for holding apart the edges of a
       wound during amputation.
   (c) (Surg.) A bandage to protect the soft parts from injury
       by the saw during amputation.
   (d) (Anat. & Zo["o]l.) A muscle serving to draw in any organ
       or part. See Illust. under {Phylactol[ae]mata}.

Source : WordNet®

retractor
     n : surgical instrument that holds back the edges of a surgical
         incision