/ Dictionary / Index J Joule-Thomson effect: Meaning and Definition of Find definitions for: Joule'-Thom'son effect" Pronunciation: ( jl'tom'sun, joul'-), [key] — Thermodynam. Thermodynam. the change of temperature that a gas exhibits during a throttling process, shown by passing the gas through a small aperture or porous plug into a region of low pressure. Cf. free expansion. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Joule's law jounce Related Content Daily Word Quiz: placid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language