noun (n)

• activities that are enjoyable or amusing(noun.act)

  Example:
  I do it for the fun of it.
  He is fun to have around.
  

  Synonym:
  merriment, playfulness
  

  source: wordnet30
• verbal wit or mockery (often at another's expense but not to be taken seriously)(noun.communication)

  Example:
  He became a figure of fun.
  

  Synonym:
  play, sport
  

  source: wordnet30
• violent and excited activity(noun.act)

  Example:
  She asked for money and then the fun began.
  They began to fight like fun.
  

  Synonym:
  hell, sin
  

  source: wordnet30
• a disposition to find (or make) causes for amusement(noun.attribute)

  Example:
  He was fun to be with.
  

  Synonym:
  playfulness
  

  source: wordnet30
• Sport; merriment; frolicsome amusement.(noun)

  source: webster1913