mountaintop vs zenith

mountaintop

noun
  • The summit of a mountain. 

adj
  • Situated or occurring on the summit of a mountain. 

zenith

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

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

  • Highest point or state; peak. 

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