From WordNet (r) 3.0 (2006):
perturb
v 1: disturb in mind or make uneasy or cause to be worried or
alarmed; "She was rather perturbed by the news that her
father was seriously ill" [syn: perturb, unhinge,
disquiet, trouble, cark, distract, disorder]
2: disturb or interfere with the usual path of an electron or
atom; "The electrons were perturbed by the passing ion"
3: cause a celestial body to deviate from a theoretically
regular orbital motion, especially as a result of interposed
or extraordinary gravitational pull; "The orbits of these
stars were perturbed by the passings of a comet"
4: throw into great confusion or disorder; "Fundamental
Islamicists threaten to perturb the social order in Algeria
and Egypt" [syn: perturb, derange, throw out of kilter]