Perturbation (biology)
WordNet
noun
(1) The act of causing disorder
(2) A disposition that is confused or nervous and upset
(3) Activity that is an intrusion or interruption
"He looked around for the source of the disturbance"
"There was a disturbance of neural function"
(4) (physics) a secondary influence on a system that causes it to deviate slightly
(5) An unhappy and worried mental state
"There was too much anger and disturbance"
"She didn't realize the upset she caused me"