sever vs uncouple

sever

verb
  • To disconnect; to disunite; to terminate. 

  • To make a separation or distinction; to distinguish. 

  • To cut free. 

  • To suffer disjunction; to be parted or separated. 

uncouple

verb
  • To disconnect or detach one thing from another. 

  • To come loose. 

  • To loose, as dogs, from their couples. 

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