/ Dictionary / Index B barium: Meaning and Definition of Find definitions for: bar•i•um Pronunciation: (bâr'ē-um, bar'-), [key] — n. Chem. a whitish, malleable, active, divalent, metallic element, occurring in combination chiefly as barite or as witherite. Symbol: Ba; at. wt.: 137.34; at. no.: 56; sp. gr.: 3.5 at 20°C. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: barium (Thesaurus) baritone clef barium 140 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