/ Dictionary / Index G Gay-Lussac's law: Meaning and Definition of Find definitions for: Gay'-Lussac's' law' Pronunciation: [key] — Thermodynamics. Thermodynamics. the principle that, for relatively low pressures, the density of an ideal gas at constant pressure varies inversely with the absolute temperature of the gas. Also calledCf. Boyle's law. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Gay-Lussac gaylussite Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language