cave in vs protest

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. 

protest

verb
  • To call as a witness in affirming or denying, or to prove an affirmation; to appeal to. 

  • to make a solemn written declaration, in due form, on behalf of the holder, against all parties liable for any loss or damage to be sustained by non-acceptance or non-payment of (a bill or note). This should be made by a notary public, whose seal it is the usual practice to affix. 

  • To affirm (something). 

  • To object to. 

  • To make a strong objection. 

noun
  • The noting by a notary public of an unpaid or unaccepted bill. 

  • A written declaration, usually by the master of a ship, stating the circumstances attending loss or damage of ship or cargo, etc. 

  • A formal objection, especially one by a group. 

  • A collective gesture of disapproval; a demonstration. 

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