Antonyms of adj flammable

1 sense of flammable

Sense 1
flammable, inflammable -- (easily ignited)

INDIRECT (VIA combustible) -> noncombustible, incombustible -- (not capable of igniting and burning)

Similarity of adj flammable

1 sense of flammable

Sense 1
flammable, inflammable -- (easily ignited)
       => combustible (vs. noncombustible) -- (capable of igniting and burning)