The Collaborative International Dictionary of English v.0.48:

Plasticity \Plas*tic"i*ty\, n. [Cf. F. plasticit['e].]
   1. The quality or state of being plastic.
      [1913 Webster]

   2. (Physiol.) Plastic force. --Dunglison.
      [1913 Webster] Plastid

WordNet (r) 3.0 (2006):

plasticity
    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]