perturbation (
http://definr.com/perturbation)
n 1: an unhappy and worried mental state; "there was too much
anger and disturbance"; "she didn't realize the upset
she caused me" [syn:
disturbance,
upset]
2: activity that is an intrusion or interruption; "he looked
around for the source of the disturbance"; "there was a
disturbance of neural function" [syn:
disturbance]
3: a disposition that is confused or nervous and upset [syn:
fluster]
4: the act of causing disorder [syn:
disruption]