noun (n)

• a document appraising the value of something (as for insurance or taxation)(noun.communication)

  Synonym:
  appraisal, estimate
  

  source: wordnet30
• the respect with which a person is held(noun.cognition)

  Example:
  They had a high estimation of his ability.
  

  Synonym:
  estimate
  

  source: wordnet30
• an approximate calculation of quantity or degree or worth(noun.cognition)

  Synonym:
  approximation, estimate, idea
  

  source: wordnet30
• a judgment of the qualities of something or somebody(noun.act)

  Example:
  In my estimation the boy is innocent.
  

  source: wordnet30
• The act of estimating.(noun)

  source: webster1913