Source : Webster's Revised Unabridged Dictionary (1913)

Breton \Bret"on\, a. [F. breton.]
   Of or relating to Brittany, or Bretagne, in France. -- n. A
   native or inhabitant of Brittany, or Bretagne, in France;
   also, the ancient language of Brittany; Armorican.

Source : WordNet®

Breton
     n 1: a native or inhabitant of Brittany (especially one who
          speaks the Breton language)
     2: a Celtic language of Brittany