noun (n)

• an approximate calculation of quantity or degree or worth(noun.cognition)

  Synonym:
  estimate, estimation, idea
  

  source: wordnet30
• the quality of coming near to identity (especially close in quantity)(noun.attribute)

  source: wordnet30
• an imprecise or incomplete account(noun.communication)

  Example:
  Newspapers gave only an approximation of the actual events.
  

  source: wordnet30
• the act of bringing near or bringing together especially the cut edges of tissue(noun.act)

  Synonym:
  bringing close together
  

  source: wordnet30
• The act of approximating; a drawing, advancing or being near; approach; also, the result of approximating.(noun)

  source: webster1913