Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

pugnacious
     adj 1: tough and callous by virtue of experience [syn: {hard-bitten},
             {hard-boiled}]
     2: ready and able to resort to force or violence; "pugnacious
        spirits...lamented that there was so little prospect of an
        exhilarating disturbance"- Herman Melville; "they were
        rough and determined fighting men" [syn: {rough}]