/ Dictionary / Index I incombustible: Meaning and Definition of Find definitions for: in•com•bus•ti•ble Pronunciation: (in"kum-bus'tu-bul), [key] — adj. not combustible; incapable of being burned; fireproof. —n. an incombustible substance. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: incombustible (Thesaurus) incoherent income Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language