altitude vs dropped ceiling

altitude

noun
  • A vertical distance. 

  • The absolute height of a location, usually measured from sea level. 

  • The angular distance of a heavenly body above our Earth's horizon. 

  • Height of rank or excellence; superiority. 

  • Highest point or degree. 

  • The distance measured perpendicularly from a figure's vertex to the opposite side of the vertex. 

dropped ceiling

noun
  • A secondary ceiling, suspended from above, used to conceal wiring, plumbing and ducts 

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