backstair vs thieving

backstair

adj
  • clandestine, secret or furtive 

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

thieving

adj
  • That thieves; that steals; inclined to steal 

noun
  • The action of theft. 

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