knock back vs rebuff

knock back

verb
  • To reject; to refuse. 

  • To drink an alcoholic beverage swiftly or often. 

  • To stun; to surprise. 

  • To press or knead (dough) so as to remove air bubbles. 

rebuff

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

  • To buff again. 

noun
  • Repercussion, or beating back. 

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

  • A sudden resistance or refusal. 

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