incombustible

adj, noun — 2 senses

incombustible

adj

/ˌɪŋkəmˈbʌstɪbəl/

Etymology From in- + combust + -ible.

1

Not capable of catching fire and burning; not flammable.

The ash represents the more incombustible mineral matter, usually of the nature of clay or slate.1921, Charles Kenneth Leith, The Economic Aspect of Geology, page 124:

Antonyms: combustible, flammable, inflammable
Derived terms: incombustibleness, incombustibly

incombustible

noun

Etymology From in- + combust + -ible.

1

Any substance that is not flammable.

Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.