fluster vs perturbation

fluster

noun
  • A state of being flustered; overwrought confusion. 

verb
  • To confuse; befuddle; throw into panic by making overwrought with confusion. 

  • To be in a heat or bustle; to be agitated and confused. 

perturbation

noun
  • Agitation; the state of being perturbed 

  • Variation in an orbit due to the influence of external bodies 

  • A small change in a physical system, or more broadly any definable system (such as a biological or economic system) 

How often have the words fluster and perturbation occurred in a corpus of books? (source: Google Ngram Viewer )