The Collaborative International Dictionary of English v.0.48:

Swashbuckler \Swash"buc`kler\, n.
   A bully or braggadocio; a swaggering, boastful fellow; a
   swaggerer. --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

swashbuckler
    n 1: a reckless impetuous irresponsible person [syn:
         daredevil, madcap, hothead, swashbuckler,
         lunatic, harum-scarum]