firebomb vs ignite

firebomb

verb
  • To attack with a firebomb. 

noun
  • A weapon that causes fire; an incendiary weapon. 

ignite

verb
  • to commence burning. 

  • to spark off (something), to trigger 

  • to set fire to (something), to light (something) 

  • To subject to the action of intense heat; to heat strongly; often said of incombustible or infusible substances. 

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