merge vs sever

merge

verb
  • To combine into a whole. 

  • To blend gradually into something else. 

noun
  • The joining together of multiple sources. 

sever

verb
  • To make a separation or distinction; to distinguish. 

  • To disconnect; to disunite; to terminate. 

  • To cut free. 

  • To suffer disjunction; to be parted or separated. 

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