1. (

• disturbance ,
• perturbation ,
• upset

) an unhappy and worried mental state; "there was too much anger and disturbance"; "she didn't realize the upset she caused me" ;

2. (

• perturbation

) (physics) a secondary influence on a system that causes it to deviate slightly ;

3. (

• perturbation ,
• disturbance

) activity that is a malfunction, intrusion, or interruption; "the term `distress' connotes some degree of perturbation and emotional upset"; "he looked around for the source of the disturbance"; "there was a disturbance of neural function" ;

4. (

• perturbation ,
• fluster

) a disposition that is confused or nervous and upset ;

5. (

• disruption ,
• perturbation

) the act of causing disorder ;