The Collaborative International Dictionary of English v.0.48:

Crystallize \Crys"tal*lize\ (kr[i^]s"tal*l[imac]z), v. t. [imp.
   & p. p. Crystallized (-l[imac]zd); p. pr. & vb. n.
   Crystallizing.] [Cf. F. cristalliser. See Crystal.]
   To cause to form crystals, or to assume the crystalline form.
   [1913 Webster]

WordNet (r) 3.0 (2006):

crystallizing
    n 1: the formation of crystals [syn: crystallization,
         crystallisation, crystallizing]