Source : Webster's Revised Unabridged Dictionary (1913)

Fighter \Fight"er\, n. [AS. feohtere.]
   One who fights; a combatant; a warrior. --Shak.

Source : WordNet®

fighter
     n 1: someone who fights (or is fighting) [syn: {combatant}, {battler},
           {belligerent}, {scrapper}]
     2: a high-speed military or naval airplane designed to destroy
        enemy aircraft in the air [syn: {fighter aircraft}, {attack
        aircraft}]
     3: someone who fights for a cause [syn: {champion}, {hero}, {paladin}]