The Collaborative International Dictionary of English v.0.48:

Steadfastness \Stead"fast*ness\, n.
   The quality or state of being steadfast; firmness; fixedness;
   constancy. "The steadfastness of your faith." --Col. ii. 5.
   [1913 Webster]

         To prove her wifehood and her steadfastness. --Chaucer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

steadfastness
    n 1: loyalty in the face of trouble and difficulty [syn:
         steadfastness, staunchness]
    2: steadfast resolution