substituent: Meaning and Definition of

sub•stit•u•ent

Pronunciation: (sub-stich'-unt), [key]
— n.
  1. an atom or atomic group that takes the place of another atom or group present in the molecule of the original compound.
—adj.
  1. having been or capable of being substituted.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.