forbidding vs knockback

forbidding

noun
  • The act by which something is forbidden; a prohibition. 

adj
  • Appearing to be threatening, unfriendly or potentially unpleasant. 

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. 

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