The Collaborative International Dictionary of English v.0.48:

Conventionalize \Con*ven"tion*al*ize\, v. t. [imp. & p. p.
   Conventionalized; p. pr. & vb. n. Conventionalizing.]
   1. To make conventional; to bring under the influence of, or
      cause to conform to, conventional rules; to establish by
      usage. [Also spelled conventionalise.]
      [1913 Webster]

   2. (Fine Arts)
      (a) To represent by selecting the important features and
          those which are expressible in the medium employed,
          and omitting the others.
      (b) To represent according to an established principle,
          whether religious or traditional, or based upon
          certain artistic rules of supposed importance.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Conventionalize \Con*ven"tion*al*ize\, v. i. (Fine Arts)
   To make designs in art, according to conventional principles.
   Cf. Conventionalize, v. t., 2.
   [1913 Webster]

WordNet (r) 3.0 (2006):

conventionalize
    v 1: make conventional or adapt to conventions;
         "conventionalized behavior" [syn: conventionalize,
         conventionalise]
    2: represent according to a conventional style; "a stylized
       female head" [syn: stylize, stylise, conventionalize]