perturbation

Agitation; the state of being perturbed.

Reſtore your ſelues, vnto your temper, Fathers; / And, vvithout perturbation, heare me ſpeake: […]

But her mind had never been in such perturbation; and it needed a very strong effort to appear attentive and cheerful till the usual hour of separating allowed her the relief of quiet reflection.

A small change in a physical system, or more broadly any definable system (such as a biological or economic system).

Natures that haue much Heat, and great and violent deſires and Perturbations, are not ripe for Action, till they haue paſſed the Meridian of their yeares: As it was with Iulius Cæſar, and Septimius Seuerus.

Variation in an orbit due to the influence of external bodies.