The Collaborative International Dictionary of English v.0.48:

Stultify \Stul"ti*fy\, v. t. [imp. & p. p. Stultified; p. pr.
   & vb. n. Stultifying.] [L. stultus foolish + -fy.]
   1. To make foolish; to make a fool of; as, to stultify one by
      imposition; to stultify one's self by silly reasoning or
      conduct. --Burke.
      [1913 Webster]

   2. To regard as a fool, or as foolish. [R.]
      [1913 Webster]

            The modern sciolist stultifies all understanding but
            his own, and that which he conceives like his own.
      --Hazlitt.
      [1913 Webster]

   3. (Law) To allege or prove to be of unsound mind, so that
      the performance of some act may be avoided.
      [1913 Webster]