/ Dictionary / Index S substituent: Meaning and Definition of Find definitions for: sub•stit•u•ent Pronunciation: (sub-stich'-unt), [key] — n. an atom or atomic group that takes the place of another atom or group present in the molecule of the original compound. —adj. having been or capable of being substituted. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. substation substitute Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language