The Collaborative International Dictionary of English v.0.48:

Gamecock \Game"cock`\ (g[=a]m"k[o^]k`), n. (Zool.)
   The male game fowl.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gamecock
    n 1: a cock bred and trained for fighting [syn: gamecock,
         fighting cock]
    2: someone who is a very fierce fighter [syn: hell-kite,
       hell-rooster, gamecock]