extremity vs severity

extremity

noun
  • An extreme measure. 

  • The most extreme or furthest point of something. 

  • A hand or foot. 

  • A limb (“major appendage of a human or animal such as an arm, leg, or wing”). 

severity

noun
  • The state of being severe. 

  • The degree of something undesirable; badness or seriousness. 

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