basement vs subfloor

basement

noun
  • A floor of a building below ground level. 

  • Last place in a sports conference standings. 

  • A mass of igneous or metamorphic rock forming the foundation over which a platform of sedimentary rocks is laid. 

subfloor

noun
  • The floor structure supporting and underlying the visible flooring or other finishing surface such as a carpet 

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