The Collaborative International Dictionary of English v.0.48:

Pugnacious \Pug*na"cious\, a. [L. pugnax, -acis, fr. pugnare to
   fight. Cf. Pugilism, Fist.]
   Disposed to fight; inclined to fighting; quarrelsome;
   fighting. --Pug*na"cious*ly, adv. -- Pug*na"cious*ness,
   n.
   [1913 Webster]