Wiktionary
non-flammable
a. not flammable; not inflammable; not able to burn easily
Usage examples of "non-flammable".
Reef-rock was resilient and non-flammable, but the shells must have been spiked with some chemical agent tailored to inflict damage beyond the reach of mere heat and percussion, because the results looked less like shattered buildings than mine tailings dumped on empty lots.