Source : Webster's Revised Unabridged Dictionary (1913)

Mutability \Mu`ta*bil"i*ty\, n. [L. mutabilitas: cf. F.
   mutabilit['e].]
   The quality of being mutable, or subject to change or
   alteration, either in form, state, or essential character;
   susceptibility of change; changeableness; inconstancy;
   variation.

         Plato confessed that the heavens and the frame of the
         world are corporeal, and therefore subject to
         mutability.                              --Stillingfleet.

Source : WordNet®

mutability
     n : the quality of being capable of mutation [syn: {mutableness}]
         [ant: {immutability}, {immutability}]