verb (v)

• prove to be of unsound mind or demonstrate someone's incompetence(verb.emotion)

  Example:
  Nobody is legally allowed to stultify himself.
  

  source: wordnet30
• cause to appear foolish(verb.communication)

  source: wordnet30
• deprive of strength or efficiency; make useless or worthless(verb.change)

  Synonym:
  cripple
  

  source: wordnet30
• To make foolish; to make a fool of; as, to stultify one by imposition; to stultify one's self by silly reasoning or conduct.(verb)

  source: webster1913