backbite vs knock

backbite

verb
  • To attack from behind or when out of earshot with spiteful or defamatory remarks. 

  • To speak badly of an absent individual. 

  • To make spiteful slanderous or defamatory statements about someone. 

noun
  • One who engages in backbiting; a backbiter. 

knock

verb
  • To criticize verbally; to denigrate; to undervalue. 

  • To kick a ball towards another player; to pass. 

  • To rap one's knuckles against something, especially wood. 

noun
  • An abrupt rapping sound, as from an impact of a hard object against wood. 

  • A sharp impact. 

  • A batsman's innings. 

  • A blow or setback. 

  • Preignition, a type of abnormal combustion occurring in spark ignition engines caused by self-ignition; also, the characteristic knocking sound associated with it. 

  • Synonym of hunger knock 

  • A criticism. 

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