noun (n)

• the state of being inactive(noun.state)

  Synonym:
  inaction, inactiveness
  Antonym:
  action, activeness, activity
  

  source: wordnet30
• a disposition to remain inactive or inert(noun.attribute)

  Synonym:
  inactiveness, inertia
  Antonym:
  activeness, activity
  

  source: wordnet30
• being inactive; being less active(noun.act)

  Antonym:
  activity
  

  source: wordnet30
• The state or quality of being inactive; inertness; as, the inactivity of matter.(noun)

  source: webster1913