fluctuation vs oscillation

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. 

oscillation

noun
  • the act of oscillating or the state of being oscillated 

  • (of a function) defined for each point x in the domain of the function by inf diam(f(U))∣Uisaneighborhoodofx, and describes the difference (possibly ∞) between the limit superior and limit inferior of the function near that point. 

  • a single such cycle 

  • a regular periodic fluctuation in value about some mean 

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