knockback vs veto

knockback

noun
  • A rejection; a refusal. 

  • A blow that causes the recipient to fall or move backwards, a knock back; a recoil. 

  • Something that impedes or reverses progress; a setback. 

veto

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

  • 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. 

verb
  • To use a veto against. 

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