heatproof vs noncombustible

heatproof

adj

  • insulating and incombustible 

verb

  • To make insulating and incombustible. 

noncombustible

adj

  • That will not readily ignite and burn. 

noun

  • Any substance that is not combustible. 

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