declension vs knockback

declension

noun
  • A falling off, decay or descent. 

  • A way of categorizing nouns, pronouns, or adjectives according to the inflections they receive. 

  • The product of that act; a list of declined forms. 

  • The act of declining a word; the act of listing the inflections of a noun, pronoun or adjective in order. 

knockback

noun
  • A blow that causes the recipient to fall or move backwards, a knock back; a recoil. 

  • A rejection; a refusal. 

  • Something that impedes or reverses progress; a setback. 

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