extremity vs zenith

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. 

zenith

noun
  • Highest point or state; peak. 

  • The point in the sky vertically above a given position or observer; the point in the celestial sphere opposite the nadir. 

  • The highest point in the sky reached by a celestial body. 

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