The Collaborative International Dictionary of English v.0.48:

Pugnacity \Pug*nac"i*ty\, n. [L. pugnacitas: cf. F.
   pugnacit['e].]
   Inclination or readiness to fight; quarrelsomeness. " A
   national pugnacity of character." --Motley.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pugnacity
    n 1: a natural disposition to be hostile [syn: aggressiveness,
         belligerence, pugnacity]