Per`tur*ba"tion (?), n. [L. perturbatio: cf. F. perturbation.]
The act of perturbing, or the state of being perturbed; esp., agitation of mind.
A disturbance in the regular elliptic or other motion of a heavenly body, produced by some force additional to that which causes its regular motion; as, the perturbations of the planets are caused by their attraction on each other.
© Webster 1913.