noun (n)

• the state of being sensitive (as to an antigen)(noun.state)

  Synonym:
  sensitisation
  

  source: wordnet30
• (psychology) the process of becoming highly sensitive to specific events or situations (especially emotional events or situations)(noun.process)

  source: wordnet30
• rendering an organism sensitive to a serum by a series of injections(noun.act)

  Synonym:
  sensitisation, sensitising, sensitizing
  

  source: wordnet30