- (uncountable) Agitation; the state of being perturbed
- (countable) A small change in a physical system, or more broadly any definable system (such as a biological or economic system)
- 1625, Francis Bacon, “Of Youth and Age. XLII.”, in The Essayes or Covncils, Civill and Moral, […] Newly Written, London: Printed by Iohn Haviland for Hanna Barret, OCLC 863521290 ↗; newly enlarged edition, London: Printed by Iohn Haviland, […], 1632, OCLC 863527675 ↗, pages 247–248 ↗:
- 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.
- (countable, astronomy, physics) Variation in an orbit due to the influence of external bodies