Source : Webster's Revised Unabridged Dictionary (1913)

Six-shooter \Six"-shoot`er\, n.
   A pistol or other firearm which can be fired six times
   without reloading especially, a six-chambered revolver.
   [Colloq. U.S.]

Source : WordNet®

six-shooter
     n : a pistol with a revolving cylinder (usually having six
         chambers for bullets) [syn: {revolver}, {six-gun}]