Perturbation

n. worry, concern, alarm; agitation, disturbance, agitation; bewilderment, act of perplexing

Perturbation may refer to any of numerous concepts in several fields:A verb in the English language, meaning to annoy or disturb (Example: "Tim and Matt were perturbing James.")Perturbation theory, mathematical methods that give approximate solutions to problems that cannot be solved exactlyPerturbation (geology), changes in the nature of alluvial deposits over timePerturbation (astronomy), alterations to an object's orbit caused by gravitational interactions with other bodiesPerturbation theory (quantum mechanics), a set of approximation schemes directly related to mathematical perturbation for describing a complicated quantum system in terms of a simpler onePerturbation (biology), an alteration of the function of a biological system, induced by external or internal mechanismsPerturbation (Machine Learning), making changes in the dataset to (re)learn a classifier (used in bagging and boosting)
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Noun
1. an unhappy and worried mental state; "there was too much anger and disturbance"; "she didn't realize the upset she caused me"
(synonym) disturbance, upset
(hypernym) agitation
(derivation) perturb, unhinge, disquiet, trouble, cark, distract, disorder
2. (physics) a secondary influence on a system that causes it to deviate slightly
(hypernym) influence
(hyponym) variation
(derivation) perturb
(classification) physics, physical science, natural philosophy
3. activity that is an intrusion or interruption; "he looked around for the source of the disturbance"; "there was a disturbance of neural function"
(synonym) disturbance
(hypernym) activity
(hyponym) fuss, trouble, bother, hassle
4. a disposition that is confused or nervous and upset
(synonym) fluster
(hypernym) discomposure
(derivation) perturb, unhinge, disquiet, trouble, cark, distract, disorder
5. the act of causing disorder
(synonym) disruption
(hypernym) disturbance
(hyponym) dislocation, breakdown
(derivation) perturb

n. disruption, disturbance, perturbation, upheaval, distemper, interference

(n.)
The act of perturbing, or the state of being perturbed; esp., agitation of mind.
  

(n.)
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.