burnable vs pilot light

burnable

noun
  • Anything that can be burned. 

adj
  • Able to be burned; combustible 

pilot light

noun
  • A small, persistent flame used to ignite gas. 

  • A small telltale lamp on a dynamo or battery circuit whose brightness indicates the voltage of the current. 

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