verb (v)

• notify of danger, potential harm, or risk(verb.communication)

  Example:
  The director warned him that he might be fired.
  The doctor warned me about the dangers of smoking.
  

  source: wordnet30
• admonish or counsel in terms of someone's behavior(verb.communication)

  Example:
  I warned him not to go too far.
  I warn you against false assumptions.
  She warned him to be quiet.
  

  Synonym:
  admonish, discourage, monish
  

  source: wordnet30
• ask to go away(verb.communication)

  Example:
  The old man warned the children off his property.
  

  source: wordnet30
• notify, usually in advance(verb.communication)

  Example:
  I warned you that I would ask some difficult questions.
  

  source: wordnet30
• To refuse.(verb)

  source: webster1913
• To make ware or aware; to give previous information to; to give notice to; to notify; to admonish; hence, to notify or summon by authority; as, to warn a town meeting; to warn a tenant to quit a house.(verb)

  source: webster1913