hard-boiled vs tough-nut

hard-boiled

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

  • Cooked to a solid consistency. 

  • Callous and unsentimental. 

tough-nut

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