1 throw into confusion or disorder.
2 disturb mentally; agitate.
3 Physics & Math. subject (a physical system, or a set of equations, or its solution) to a perturbation.
Derivatives:
perturbable adj. perturbative adj. perturbingly adv.
Etymology: ME f. OF pertourber f. L (as PER-, turbare disturb)
Useful english dictionary. 2012.