Source : Webster's Revised Unabridged Dictionary (1913)

Executioner \Ex`e*cu"tion*er\, n.
   1. One who executes; an executer. --Bacon.

   2. One who puts to death in conformity to legal warrant, as a
      hangman.

Source : WordNet®

executioner
     n : an official who inflicts capital punishment in pursuit of a
         warrant [syn: {public executioner}]