backstair vs grave

backstair

adj
  • clandestine, secret or furtive 

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

grave

adj
  • Serious, in a negative sense; important, formidable. 

  • Low in pitch, tone etc. 

  • Characterised by a dignified sense of seriousness; not cheerful. 

noun
  • Death, destruction. 

  • Any place of interment; a tomb; a sepulcher. 

  • Deceased people; the dead. 

  • An excavation in the earth as a place of burial 

  • A written accent used in French, Italian, and other languages. è is an e with a grave accent (`). 

  • A count, prefect, or person holding office. 

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