eon vs eternity

eon

noun
  • A long period of time. 

  • A period of 1,000,000,000 years. 

  • The longest geochronologic unit, being a period of hundreds of millions of years; subdivided into eras. 

  • Eternity. 

  • A spirit being emanating from the Godhead. 

eternity

noun
  • A comparatively long time. 

  • Existence without end, infinite time. 

  • A period of time which extends infinitely far into the future. 

  • The remainder of time that elapses after death. 

  • Existence outside of time. 

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