rejuvenation vs rejuvenescence

rejuvenation

noun
  • The process of rendering young again. 

  • The process of producing beneficial changes. 

rejuvenescence

noun
  • A renewal of youthful characteristics or vitality. 

  • The escape of the protoplasm of a cell and its conversion into a cell of a different character, as in certain algae. 

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