noun (n)

• the state of having good sense and sound judgment(noun.state)

  Example:
  His rationality may have been impaired.
  

  Synonym:
  reason, reasonableness
  

  source: wordnet30
• the quality of being consistent with or based on logic(noun.attribute)

  Synonym:
  rationalness
  

  source: wordnet30
• The quality or state of being rational; agreement with reason; possession of reason; due exercise of reason; reasonableness.(noun)

  source: webster1913