insulate vs sever

insulate

verb
  • To separate, detach, or isolate. 

  • To separate a body or material from others, e.g. by non-conductors to prevent the transfer of electricity, heat, etc. 

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 insulate and sever occurred in a corpus of books? (source: Google Ngram Viewer )