Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun combustible

1 sense of combustible

Sense 1
combustible, combustible material -- (a substance that can be burned to provide heat or power)
       => fuel -- (a substance that can be consumed to produce energy; "more fuel is needed during the winter months"; "they developed alternative fuels for aircraft")

Antonyms of adj combustible

1 sense of combustible

Sense 1
combustible (vs. noncombustible) -- (capable of igniting and burning)

noncombustible (vs. combustible), incombustible -- (not capable of igniting and burning)
        => fireproof -- (impervious to damage by fire)
        => fire-retardant, fire-resistant, fire-resisting, fire-resistive -- (difficult to burn)
        => flameproof, flame-retardant -- (resistant to catching fire)
        => nonflammable -- (impossible to ignite)

Similarity of adj combustible

1 sense of combustible

Sense 1
combustible (vs. noncombustible) -- (capable of igniting and burning)
       => burnable, ignitable, ignitible -- (capable of burning)
       => comburent, comburant, combustive -- (supporting combustion)
       => flammable, inflammable -- (easily ignited)
       => ignescent -- (can emit sparks or burst into flame)
       => incendiary -- (capable of catching fire spontaneously or causing fires or burning readily; "an incendiary agent"; "incendiary bombs")