extremity vs tail end

extremity

noun
  • 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”). 

  • An extreme measure. 

tail end

noun
  • The hindmost part of anything (a person, animal, or object), the rear end; the butt, buttocks; hindquarters, rump. 

  • The last part of a period of time, event, or situation; the concluding or final part. 

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