cold shoulder vs knockback

cold shoulder

noun
  • A deliberate act of disrespect; a slight or snub 

verb
  • To deliberately slight or snub someone. 

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 cold shoulder and knockback occurred in a corpus of books? (source: Google Ngram Viewer )