downfall vs pile-up

downfall

noun
  • A precipitous decline in fortune; death or rapid deterioration, as in status or wealth. 

  • The cause of such a fall; a critical blow or error. 

  • An act of falling down. 

verb
  • To fall down; deteriorate; decline. 

pile-up

noun
  • An accumulation that occurs over time, especially one which is not welcome. 

  • A pile of tackling players. 

  • A pile of crashed vehicles due to a traffic accident. 

How often have the words downfall and pile-up occurred in a corpus of books? (source: Google Ngram Viewer )