noun (n)

• the state of impairing the quality or reducing the value of something(noun.state)

  Synonym:
  alloy
  

  source: wordnet30
• an additional ingredient that is added by mixing with the base(noun.artifact)

  Example:
  The growing medium should be equal parts of sand and loam with an admixture of peat moss and cow manure.
  

  Synonym:
  intermixture
  

  source: wordnet30
• the act of mixing together(noun.act)

  Synonym:
  commixture, intermixture, mix, mixing, mixture
  

  source: wordnet30
• The act of mixing; mixture.(noun)

  source: webster1913