slave-driver vs warden

slave-driver

noun
  • An overseer of slaves at work; a person who puts slaves to work. 

  • An employer who demands excessive amounts of work from employees. 

warden

noun
  • A governing official in various institutions 

  • An official charged with supervisory duties or with the enforcement of specific laws or regulations; such as a game warden or air-raid warden 

  • A variety of pear. 

  • A chief administrative officer of a prison. 

verb
  • To carry out the duties of a warden. 

How often have the words slave-driver and warden occurred in a corpus of books? (source: Google Ngram Viewer )