revoke vs warn

revoke

verb
  • To cancel or invalidate by withdrawing or reversing. 

noun
  • The act of revoking in a game of cards. 

  • A violation ranked in seriousness somewhat below overt cheating, with the status of a more minor offense only because, when it happens, it is usually accidental. 

  • A renege; a violation of important rules regarding the play of tricks in trick-taking card games serious enough to render the round invalid. 

warn

verb
  • To advise or order to go or stay away. 

  • To notify or inform (someone, about something). 

  • To caution or admonish (someone) against unwise or unacceptable behaviour. 

  • To give warning. 

  • To summon (someone) to or inform of a formal meeting or duty. 

  • To make (someone) aware of impending danger, evil, etc. 

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