The Collaborative International Dictionary of English v.0.48:

bullheadedness \bullheadedness\ n.
   resolute adherence to one's own ideas or desires.

   Syn: stubbornness, obstinacy, obstinance, pigheadedness,
        self-will.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

bullheadedness
    n 1: resolute adherence to your own ideas or desires [syn:
         stubbornness, bullheadedness, obstinacy,
         obstinance, pigheadedness, self-will]