Source : Webster's Revised Unabridged Dictionary (1913)

Willingness \Will"ing*ness\, n.
   The quality or state of being willing; free choice or consent
   of the will; freedom from reluctance; readiness of the mind
   to do or forbear.

         Sweet is the love which comes with willingness.
                                                  --Dryden.

Source : WordNet®

willingness
     n : cheerful compliance; "he expressed his willingness to help"
         [ant: {unwillingness}]