incombustible

 
Pronunciation: /ˌɪnkəmˈbʌstɪb(ə)l/

adjective

  • (especially of a building material or component) consisting or made of material that does not burn if exposed to fire: an incombustible floor construction

Derivatives

incombustibility

Pronunciation: /-ˈbɪlɪti/
noun

Origin:

late 15th century: from medieval Latin incombustibilis, from in- 'not' + combustibilis (see combustible)