/ Dictionary / Index S side chain: Meaning and Definition of Find definitions for: side' chain" Pronunciation: [key] — Chem. Chem. an open chain of atoms attached to an atom of a larger chain, or to a ring. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. side card side chair Related Content Daily Word Quiz: pedagogy Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language