Source : Webster's Revised Unabridged Dictionary (1913)

Tourniquet \Tour"ni*quet\, n. [F., fr. tourner to turn.] (Surg.)
   An instrument for arresting hemorrhage. It consists
   essentially of a pad or compress upon which pressure is made
   by a band which is tightened by a screw or other means.

Source : WordNet®

tourniquet
     n : bandage that stops the flow of blood from an artery by
         applying pressure [syn: {compression bandage}]