Source : Webster's Revised Unabridged Dictionary (1913)

Changeless \Change"less\, a.
   That can not be changed; constant; as, a changeless purpose.
   -- {Change"less*ness}, n.

Source : WordNet®

changelessness
     n 1: the property of remaining unchanged
     2: the quality of being unchangeable; having a marked tendency
        to remain unchanged [syn: {unchangeability}, {unchangeableness},
         {unchangingness}] [ant: {changeableness}]