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]

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "plasticity":
   adaptability, adjustability, agreeability, agreeableness,
   alterability, amenability, aptitude, aptness, bendability,
   biddability, brightness, changeability, changeableness,
   changefulness, cleverness, compliableness, docility, ductibility,
   ductility, educability, elasticity, extendibility, extensibility,
   facility, fictility, flexibility, flexility, flexuousness,
   fluidity, formativeness, give, impermanence, impressionability,
   intelligence, limberness, litheness, malleability, mobility,
   modifiability, moldability, motivation, movability, mutability,
   nonuniformity, permutability, pliability, pliancy, quickness,
   readiness, receptiveness, receptivity, resilience, responsiveness,
   rubberiness, sensibility, sensitiveness, sequacity, servility,
   springiness, submissiveness, subservience, suppleness,
   susceptibility, teachability, teachableness, tensileness,
   tensility, tractability, tractility, trainableness, transience,
   transitoriness, willingness, willowiness, yieldingness