/ Dictionary / Index O open chain: Meaning and Definition of Find definitions for: o'pen chain' Pronunciation: [key] — Chem. Chem. a series of atoms linked in a chain not joined together at its ends, and so represented in its structural formula. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. open-cast open circuit Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language