verb (v)

• cause to seem less serious; play down(verb.communication)

  Example:
  Don't belittle his influence.
  

  Synonym:
  denigrate, derogate, minimize
  

  source: wordnet30
• express a negative opinion of(verb.communication)

  Synonym:
  disparage, pick at
  Antonym:
  blandish, flatter
  

  source: wordnet30
• lessen the authority, dignity, or reputation of(verb.change)

  Example:
  Don't belittle your colleagues.
  

  Synonym:
  diminish
  

  source: wordnet30
• To make little or less in a moral sense; to speak of in a depreciatory or contemptuous way.(verb)

  source: webster1913