backstair vs hermitage

backstair

noun
  • The backstairs (stairs at the rear of a building). 

adj
  • clandestine, secret or furtive 

hermitage

noun
  • A place of seclusion. 

  • A house or dwelling where a hermit lives. 

  • A period of seclusion. 

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