/ Dictionary / Index G gastight: Meaning and Definition of Find definitions for: gas•tight Pronunciation: (gas'tīt"), [key] — adj. not penetrable by a gas. not admitting a given gas under a given pressure. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. gas thermometer gastness Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language