countermand vs retain

countermand

verb
  • To counteract, to act against, to frustrate. 

  • To recall a person or unit with such an order. 

  • To revoke (a former command); to cancel or rescind by giving an order contrary to one previously given. 

  • To cancel an order for (some specified goods). 

noun
  • An order to the contrary of a previous one. 

retain

verb
  • To hold back (a pupil) instead of allowing them to advance to the next class or year. 

  • To employ by paying a retainer. 

  • To keep in one's pay or service. 

  • To keep in possession or use. 

  • To hold secure. 

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