disassociate vs sever

disassociate

verb
  • To separate; to disunite; to disintegrate; to dissolve. 

  • To separate into smaller discrete units, as with analysis. 

  • To separate (oneself); to dissolve one's association with a person, group, or situation. 

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. 

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