cave in vs dilate

cave in

verb
  • To collapse inward or downward. 

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

noun
  • The act of relenting. 

  • The location where something has caved in. 

  • The act of something collapsing or caving in. 

dilate

verb
  • To become wider or larger; to expand. 

  • To speak largely and copiously; to dwell in narration; to enlarge; with "on" or "upon". 

  • To enlarge; to make bigger. 

  • To use a dilator to widen (something, such as a vagina). 

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