backstair vs seclusion

backstair

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

adj
  • clandestine, secret or furtive 

seclusion

noun
  • A secluded, isolated or private place. 

  • The act of secluding, shutting out or keeping apart. 

  • The mature phase of the extratropical cyclone life cycle. 

  • The state of being secluded or shut out, as from company, society, the world, etc.; solitude. 

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