knock vs let go

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. 

let go

verb
  • To ignore (a comment, etc.). 

  • To dismiss from employment. 

  • To release from one's grasp; to go from a state of holding on to a state of no longer holding on. 

  • To emotionally disengage or to distract oneself from a situation. 

  • To fail to maintain a standard of appearance, behavior, or performance. 

  • Used other than figuratively or idiomatically: see let, go. 

  • To gain weight 

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