defer vs knuckle under

defer

verb
  • To render, to offer. 

  • To submit to the opinion or desire of others in respect to their judgment or authority. 

  • To delay or postpone 

  • to postpone induction into military service. 

  • After winning the opening coin toss, to postpone until the start of the second half a team's choice of whether to kick off or receive (and to allow the opposing team to make this choice at the start of the first half). 

  • To delay, to wait. 

knuckle under

verb
  • To yield or cooperate when pressured or forced to do so. 

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