abend vs break off

abend

verb
  • To terminate abnormally. 

noun
  • The abnormal termination of a program. 

  • Termination of a process prior to completion. 

break off

verb
  • To end abruptly, either temporarily or permanently. 

  • To end a relationship. 

  • To remove a piece from a whole by breaking or snapping 

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