crosspiece vs fanlight

crosspiece

noun
  • A horizontal or transverse beam or similar member that extends across or perpendicular to something. 

  • A bar or timber connecting two knightheads or two bitts; a timber over the windlass, with pins for belaying the running rigging. 

fanlight

noun
  • a semicircular or semioval window over a door or other window, normally having a fan-like structure of ribs; sometimes hinged to the transom 

  • an electric fan, usually a ceiling fan, that is also a light fixture 

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