roof vs zenith

roof

noun
  • The top external level of a building. 

  • The external covering at the top of a building. 

  • The upper part of a cavity. 

  • An overhanging rock wall. 

  • The surface or bed of rock immediately overlying a bed of coal or a flat vein. 

verb
  • To cover or furnish with a roof. 

  • To traverse buildings by walking or climbing across their roofs. 

  • To put into prison, to bird. 

  • To shelter as if under a roof. 

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 roof and zenith occurred in a corpus of books? (source: Google Ngram Viewer )