The Collaborative International Dictionary of English v.0.48:

Gascon \Gas"con\ (?; F. ?), a. [F.]
   Of or pertaining to Gascony, in France, or to the Gascons;
   also, braggart; swaggering. -- n. A native of Gascony; a
   boaster; a bully. See Gasconade.
   [1913 Webster]