mansard roof vs roof

mansard roof

noun
  • A steeper roof that terminates into a flat roof at its high point. 

  • A roof having two slopes on each side, the lower one having a steeper pitch than the upper; this increases the volume of the enclosed space. 

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 mansard roof and roof occurred in a corpus of books? (source: Google Ngram Viewer )