noun (n)

• an unhappy and worried mental state(noun.state)

  Synonym:
  disturbance, upset
  

  source: wordnet30
• (physics) a secondary influence on a system that causes it to deviate slightly(noun.phenomenon)

  source: wordnet30
• activity that is a malfunction, intrusion, or interruption(noun.event)

  Example:
  The term `distress' connotes some degree of perturbation and emotional upset.
  

  Synonym:
  disturbance
  

  source: wordnet30
• a disposition that is confused or nervous and upset(noun.attribute)

  Synonym:
  fluster
  

  source: wordnet30
• the act of causing disorder(noun.act)

  Synonym:
  disruption
  

  source: wordnet30
• The act of perturbing, or the state of being perturbed; esp., agitation of mind.(noun)

  source: webster1913