The Collaborative International Dictionary of English v.0.48:

Obduracy \Ob"du*ra*cy\, n.
   The duality or state of being obdurate; invincible hardness
   of heart; obstinacy. "Obduracy and persistency." --Shak.
   [1913 Webster]

         The absolute completion of sin in final obduracy.
                                                  --South.
   [1913 Webster]

WordNet (r) 3.0 (2006):

obduracy
    n 1: resoluteness by virtue of being unyielding and inflexible
         [syn: adamance, obduracy, unyieldingness]