countermand vs veto

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. 

veto

verb
  • To use a veto against. 

noun
  • An invocation of that right. 

  • A technique or mechanism for discarding what would otherwise constitute a false positive in a scientific experiment 

  • A political right to disapprove of (and thereby stop) the process of a decision, a law etc. 

  • An authoritative prohibition or negative; a forbidding; an interdiction. 

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