cave in vs unwind

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. 

unwind

noun
  • Any mechanism or operation that unwinds something. 

verb
  • To undo something. 

  • To relax; to chill out; to rest and become relieved of stress 

  • To close out a position, especially a complicated position. 

  • To be or become unwound; to be capable of being unwound or untwisted. 

  • To analyse (a call stack) so as to generate a stack trace etc. 

  • To separate (something that is wound up) 

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