firmness vs hardihood

firmness

noun
  • strictness; mental strength 

  • security; steadfastness; good grip 

  • physical durability; rigidness (of material) 

hardihood

noun
  • Unyielding boldness and daring; firmness in doing something that exposes one to difficulty, danger, or calamity; intrepidness. 

  • Ability to withstand extreme conditions, hardiness. 

  • Excessive boldness; foolish daring; offensive assurance. 

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