perturbation

noun

1. an unhappy and worried mental state"there was too much anger and disturbance"
2. (physics) a secondary influence on a system that causes it to deviate slightly
3. activity that is a malfunction, intrusion, or interruption"the term ‘distress’ connotes some degree of perturbation and emotional upset"
4. a disposition that is confused or nervous and upset
5. the act of causing disorder