Source : Webster's Revised Unabridged Dictionary (1913)

Franc-tireur \Franc"-ti`reur"\, n. [F., fr. franc free + tireur
   shooter, fr. tirer to shoot.] (Mil.)
   A French partisan soldier, or one belonging to a corps of
   detached light troops engaged in forays, skirmishes,
   scouting, etc.

Source : WordNet®

franc-tireur
     n : a sharpshooter (in the French army)