The Collaborative International Dictionary of English v.0.48:
noncombustible \noncombustible\ adj. Not combustible; not able to burn; as, drapery should be made of noncombustible materials. Opposite of combustible. Syn: incombustible. [WordNet 1.5]WordNet (r) 3.0 (2006):
noncombustible adj 1: not capable of igniting and burning [syn: noncombustible, incombustible] [ant: combustible]