knockback vs rebuff

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. 

rebuff

noun
  • A sudden resistance or refusal. 

  • Repercussion, or beating back. 

  • He was surprised by her quick rebuff to his proposal. 

verb
  • To refuse; to offer sudden or harsh resistance; to turn down or shut out. 

  • To buff again. 

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