sever vs unstop

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. 

unstop

verb
  • To remove a stoppage; to clear a blockage. 

  • To draw out the stops of (an organ). 

  • To unplug or uncork a container. 

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