/ Dictionary / Index C closed system: Meaning and Definition of Find definitions for: closed' sys'tem Pronunciation: [key] — Thermodynam. Thermodynam. a region that is isolated from its surroundings by a boundary that admits no transfer of matter or energy across it. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. closed stance closed traverse Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language