Combust :: Combust (a.) So near the sun as to be obscured or eclipsed by his light, as the moon or planets when not more than eight degrees and a half from the sun..
Incombustible :: Incombustible (a.) Not combustible; not capable of being burned, decomposed, or consumed by fire; uninflammable; as, asbestus is an incombustible substance; carbon dioxide is an incombustible gas..