/ Dictionary / Index S substantia nigra: Meaning and Definition of Find definitions for: sub•stan•ti•a ni•gra Pronunciation: (sub-stan'shē-u nī'gru, nig'ru), [key] — pl. sub•stan•ti•ae ni•grae substantia nigras. a deeply pigmented area of the midbrain containing dopamine-producing nerve cells. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. substantialism substantiate Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language