headlamp vs sidelight

headlamp

noun
  • An individual headlight, particularly of a motor vehicle. 

  • A flashlight worn on the head. 

sidelight

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

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

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

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