fire-retardant vs nonexplosive

fire-retardant

adj

  • Hard to ignite; not flammable. 

noun

  • A substance that makes an object resistant to burning. 

nonexplosive

adj

  • Not explosive; unable to explode. 

How often have the words fire-retardant and nonexplosive occurred in a corpus of books? (source: Google Ngram Viewer )