hold on vs unfasten

hold on

verb
  • To persist. 

  • To remain loyal. 

  • To grasp or grip firmly. 

  • To keep; to store something for someone. 

  • Wait a short while. 

unfasten

verb
  • To come unloosed or untied. 

  • To detach from any connecting agency or link; to disconnect. 

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