backstairs vs cryptozoic

backstairs

adj
  • Secret or furtive. 

  • Scandalous. 

noun
  • An indirect or furtive means of access or intercourse. 

  • A staircase at the rear of a building or one normally only used by servants and tradesmen. 

cryptozoic

adj
  • Hidden (especially in the soil); not easily visible. 

  • Living in a cavity or small cave. 

  • Relating to a cryptozoite. 

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