slave-driver vs slaver

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. 

slaver

noun
  • A person engaged in the slave trade; a person who buys, sells, or owns slaves. 

  • A ship used to transport slaves. 

  • Saliva running from the mouth; drool. 

  • A white slaver, who sells prostitutes into illegal 'sex slavery'. 

verb
  • To smear with saliva issuing from the mouth. 

  • To be besmeared with saliva. 

  • To fawn. 

  • To drool saliva from the mouth; to slobber. 

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