verb (v)

• make tight or tighter(verb.change)

  Example:
  Tighten the wire.
  

  Synonym:
  fasten
  

  source: wordnet30
• become tight or tighter(verb.change)

  Example:
  The rope tightened.
  

  source: wordnet30
• restrict(verb.change)

  Example:
  Tighten the rules.
  

  Synonym:
  constrain, stiffen, tighten up
  

  source: wordnet30
• narrow or limit(verb.change)

  Synonym:
  reduce
  

  source: wordnet30
• To draw tighter; to straiten; to make more close in any manner.(verb)

  source: webster1913