difficulty vs extremity

difficulty

noun
  • An obstacle that hinders achievement of a goal. 

  • Physical danger from the environment, especially with risk of drowning 

  • The state of being difficult, or hard to do. 

  • An objection. 

  • An awkward situation or quarrel. 

  • That which cannot be easily understood or believed. 

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. 

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