noun (n)

• understanding of the nature or meaning or quality or magnitude of something(noun.cognition)

  Synonym:
  grasp, hold
  

  source: wordnet30
• delicate discrimination (especially of aesthetic values)(noun.cognition)

  Synonym:
  discernment, perceptiveness, taste
  

  source: wordnet30
• an expression of gratitude(noun.communication)

  Example:
  He expressed his appreciation in a short note.
  

  source: wordnet30
• a favorable judgment(noun.act)

  Synonym:
  admiration
  

  source: wordnet30
• an increase in price or value(noun.act)

  Example:
  An appreciation of 30% in the value of real estate.
  

  Antonym:
  depreciation
  

  source: wordnet30
• A just valuation or estimate of merit, worth, weight, etc.; recognition of excellence.(noun)

  source: webster1913