1 [mass noun] anxiety; mental uneasiness:she sensed her friend’s perturbation
[count noun] a cause of anxiety or uneasiness:Frank’s atheism was more than a perturbation to Michael
2a deviation of a system, moving object, or process from its regular or normal state or path, caused by an outside influence:these shifts and swings in wildlife populations are possibly related to climatic perturbations
Astronomy a minor deviation in the course of a celestial body, caused by the attraction of a neighbouring body.
late Middle English: from Latin perturbatio(n-), from the verb perturbare 'disturb greatly' (see perturb)
perturbation in other Oxford dictionaries
Definition of perturbation in the US English dictionary