plafond vs rooftop

plafond

noun
  • A ceiling, especially one that is ornately decorated. 

  • The tibial plafond. 

  • A painting or decoration on a ceiling. 

rooftop

noun
  • The area atop a roof. 

  • The top layer of a roof; the material covering or composing a roof. 

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