covert vs roofing

covert

noun
  • A covering. 

  • A disguise. 

  • A feather that covers the bases of flight feathers. 

  • Area of thick undergrowth where animals hide. 

  • A hiding place. 

adj
  • Under coverture. 

  • Secret, surreptitious, concealed. 

roofing

noun
  • Material used on the outside of a roof, such as shingles. 

  • The process of constructing a roof or roofs. 

  • A way of travel which consists in clambering over the roofs of skyscrapers. 

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