You are hardly dull my dear. A double entendre fitting the word is all-
Definition of perturbation
1 : the
action of perturbing : the state of being perturbed
2 : a disturbance of motion, course, arrangement, or state of equilibrium
especially :
a disturbance of the regular and usually elliptical course of motion of a celestial body that is produced by some force additional to that which causes its regular motion
https://www.merriam-webster.com/dictionary/perturbation