per·tur·ba·tion /ˌpɝtɚ/
  擾動
  perturbation
  擾動
  Per·tur·ba·tion n.
  1. The act of perturbing, or the state of being perturbed; esp., agitation of mind.
  2. Astron. 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.
  ◄ ►
  perturbation
       n 1: an unhappy and worried mental state; "there was too much
            anger and disturbance"; "she didn't realize the upset
            she caused me" [syn: disturbance, upset]
       2: (physics) a secondary influence on a system that causes it
          to deviate slightly
       3: activity that is an intrusion or interruption; "he looked
          around for the source of the disturbance"; "there was a
          disturbance of neural function" [syn: disturbance]
       4: a disposition that is confused or nervous and upset [syn: fluster]
       5: the act of causing disorder [syn: disruption]