What is the meaning of crazy?

noun

• Someone deranged and possibly dangerous.
  • synonyms: loony, looney, nutcase, weirdo

adjective

• Affected with madness or insanity.
  • usage: "a man who had gone mad"
  • synonyms: brainsick, demented, disturbed, mad, sick, unbalanced, unhinged
• Foolish; totally unsound.
  • usage: "a crazy scheme"; "half-baked ideas"; "a screwball proposal without a prayer of working"
  • synonyms: half-baked, screwball, softheaded
• Possessed by inordinate excitement.
  • usage: "the crowd went crazy"; "was crazy to try his new bicycle"
• Bizarre or fantastic.
  • usage: "had a crazy dream"; "wore a crazy hat"
• Intensely enthusiastic about or preoccupied with.
  • usage: "crazy about cars and racing"; "he is potty about her"
  • synonyms: wild, dotty, gaga