boarding house vs roof

boarding house

noun
  • A boarding school building where boarders live during term time. 

  • A private house in which paying residents are provided with accommodation and meals. 

roof

noun
  • The top external level of a building. 

  • The external covering at the top of a building. 

  • The upper part of a cavity. 

  • An overhanging rock wall. 

  • The surface or bed of rock immediately overlying a bed of coal or a flat vein. 

verb
  • To cover or furnish with a roof. 

  • To traverse buildings by walking or climbing across their roofs. 

  • To put into prison, to bird. 

  • To shelter as if under a roof. 

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