flash flood vs superfluity

flash flood

noun
  • A sudden, rapid flood, usually of short duration and local impact. 

superfluity

noun
  • The quality or state of being superfluous; overflowingness. 

  • Something superfluous, as a luxury. 

  • Collective noun for a group of nuns. 

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