sidelight vs top light

sidelight

noun
  • A window found at one or both sides of a door. 

  • A piece of incidental information that helps one understand a subject. 

  • A light found at the side of something; especially of a vehicle. 

top light

noun
  • The upper (and usually smaller) part (casement) of a window, often hinged a the top 

  • Any glazing above a main window, partition or door 

  • A skylight. 

  • Light from above; toplighting. 

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