fluctuation vs variance

fluctuation

noun
  • A wavering; unsteadiness. 

  • In medicine, a wave-like motion or undulation of a fluid in a natural or abnormal cavity (e.g. pus in an abscess), which is felt during palpation or percussion. 

  • A motion like that of waves; a moving in this and that direction. 

variance

noun
  • The state of differing or being in conflict. 

  • A discrepancy between two legal documents. 

  • A departure from a cause of action originally in a complaint. 

  • An official permit to do something that is ordinarily forbidden by regulations. 

  • The act of varying or the state of being variable. 

  • The number of degrees of freedom in a system. 

  • Covariance and contravariance generally. 

  • A difference between what is expected and what is observed; deviation. 

  • The second central moment in probability. 

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