naturalize vs persist

naturalize

verb
  • To make (a word) a natural part of the language, using the native homologue of each phoneme (and often for each morpheme) of the imported word (e.g., native inflections). 

  • To study nature. 

  • To limit explanations of a phenomenon to naturalistic ones and exclude supernatural ones. 

  • To grant citizenship to someone not born a citizen. 

  • To acclimatize an animal or plant. 

  • To make natural 

persist

verb
  • To go on stubbornly or resolutely. 

  • To repeat an utterance. 

  • To cause to persist; make permanent. 

  • To continue to exist. 

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