liberate vs naturalize

liberate

verb
  • To release from restraint or inhibition. 

  • To release from chemical bonds or solutions. 

  • To acquire from an enemy during wartime, used especially of cities, regions, and other population centers. 

  • To release from servitude or unjust rule. 

  • To release from slavery: to manumit. 

  • To acquire from another by theft or force: to steal, to rob. 

naturalize

verb
  • To acclimatize an animal or plant. 

  • 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 make natural 

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