cave in vs reject

cave in

verb
  • To relent; to grant approval against one's initial will. 

  • To collapse inward or downward. 

noun
  • The act of relenting. 

  • The location where something has caved in. 

  • The act of something collapsing or caving in. 

reject

verb
  • To refuse to accept. 

  • To refuse a romantic advance. 

  • To block a shot, especially if it sends the ball off the court. 

noun
  • A rejected takeoff. 

  • A rejected defective product in a production line. 

  • Something that is rejected. 

  • An unpopular person. 

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