flammable vs ignitable

flammable

adj
  • Capable of burning, especially a liquid. 

  • Subject to easy ignition and rapid flaming combustion. 

  • Easily set on fire. 

noun
  • Any flammable substance. 

ignitable

adj
  • Capable of being ignited; able to burn. 

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