hard-bitten vs hard-boiled

hard-bitten

adj
  • callous and toughened by experience 

hard-boiled

adj
  • Callous and unsentimental. 

  • Written in a laconic, dispassionate, often ironic style for a realistic, unsentimental effect. 

  • Cooked to a solid consistency. 

How often have the words hard-bitten and hard-boiled occurred in a corpus of books? (source: Google Ngram Viewer )