demonstrator vs professor

demonstrator

noun
  • The forefinger. 

  • One who demonstrates anything, or proves beyond doubt. 

  • An item, particularly a vehicle, used in demonstrations to a customer or user. 

  • An assistant to a lecturer. 

  • One who demonstrates products in a retail environment; a merchandiser. 

  • One who teaches anatomy from the dissected parts. 

  • One who takes part in a demonstration; a protester. 

professor

noun
  • The most senior rank for an academic at a university or similar institution, informally also known as "full professor." 

  • A teacher or faculty member at a college or university regardless of formal rank. 

  • A pianist in a saloon, brothel, etc. 

  • The puppeteer who performs a Punch and Judy show; a Punchman. 

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