/ Dictionary / Index A argon: Meaning and Definition of Find definitions for: ar•gon Pronunciation: (är'gon), [key] — n. Chem. a colorless, odorless, chemically inactive, monatomic, gaseous element that, because of its inertness, is used for filling fluorescent and incandescent lamps and vacuum tubes. Symbol: Ar; at. no.: 18; at. wt.: 39.948. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: argon (Thesaurus) Argolis Argonaut Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language