frailty vs sickliness

frailty

noun
  • The condition quality of being frail, physically, mentally, or morally; weakness of resolution; liability to be deceived. 

  • A fault proceeding from weakness; foible; sin of infirmity. 

sickliness

noun
  • The state or characteristic of weakness, incapacity, or physical distress due to poor health, especially of a chronic nature. 

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