enfetter vs unbind

enfetter

verb
  • To bind in fetters; to enchain. 

unbind

verb
  • To set free from a debt, contract or promise. 

  • To disable some kind of connection in software, such as a key binding. 

  • To take bindings off. 

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