/ Dictionary / Index I impermissible: Meaning and Definition of Find definitions for: im•per•mis•si•ble Pronunciation: (im"pur-mis'u-bul), [key] — adj. not permissible or allowable; unallowable. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: impermissible (Thesaurus) impermeable impers. Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language