/ Dictionary / Index S strontium: Meaning and Definition of Find definitions for: stron•ti•um Pronunciation: (stron'shē-um, -shum, -tē-um), [key] — n. Chem. a bivalent, metallic element whose compounds resemble those of calcium, found in nature only in the combined state, as in strontianite: used in fireworks, flares, and tracer bullets. Symbol: Sr; at. wt.: 87.62; at. no.: 38; sp. gr.: 2.6. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: strontium (Thesaurus) strontianite strontium 90 Related Content Daily Word Quiz: alacrity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language