noun (n)

• the process of thickening by dehydration(noun.process)

  source: wordnet30
• the act of thickening(noun.act)

  Synonym:
  thickening
  

  source: wordnet30
• The act or the process of inspissating, or thickening a fluid substance, as by evaporation; also, the state of being so thickened.(noun)

  source: webster1913