dissociate vs sever

dissociate

verb
  • To undergo dissociation. 

  • To part; to stop associating. 

  • To separate compounds into simpler component parts, usually by applying heat or through electrolysis. 

  • To make unrelated; to sever a connection; to separate. 

sever

verb
  • To suffer disjunction; to be parted or separated. 

  • To disconnect; to disunite; to terminate. 

  • To make a separation or distinction; to distinguish. 

  • To cut free. 

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