knockback vs nonacceptance

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. 

nonacceptance

noun
  • A neglect or refusal to accept. 

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