The Collaborative International Dictionary of English v.0.48:

Malleability \Mal"le*a*bil"i*ty\, n. [CF. F.
   mall['e]abilit['e].]
   The quality or state of being malleable; -- opposed to
   friability and brittleness. --Locke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

malleability
    n 1: the property of being physically malleable; the property of
         something that can be worked or hammered or shaped without
         breaking [syn: malleability, plasticity] [ant:
         unmalleability]