infirm vs weakly

infirm

adj
  • Frail; unstable; insecure. 

  • Weak or ill, not in good health. 

  • Irresolute; weak of mind or will. 

verb
  • To contradict, to provide proof that something is not. 

weakly

adj
  • Frail, sickly or of a delicate constitution; weak. 

adv
  • With little strength or force. 

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