Professor vs pupil

Professor

noun
  • The title for someone who holds the professor job. 

pupil

noun
  • One who studies under supervision of a renowned expert in their field. 

  • A learner at a school under the supervision of a teacher. 

  • The central dark part of an ocellated spot. 

  • The hole in the middle of the iris of the eye, through which light passes to be focused on the retina. 

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