cave in vs constipation

cave in

noun
  • The act of something collapsing or caving in. 

  • The act of relenting. 

  • The location where something has caved in. 

verb
  • To collapse inward or downward. 

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

constipation

noun
  • The act of crowding anything into a lesser space, or the state of being crowded or pressed together; condensation. 

  • A state of the bowels in which the evacuations are infrequent and difficult, or the intestines become filled with hardened faeces 

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