strontium

UK: /ˈstrɒntɪəm/ US: (stron′shē əm, -shəm, -tē əm)

WordReference Random House Unabridged Dictionary of American English © 2025

stron•ti•um  (stron′shē əm, -shəm, -tē əm), n. [Chem.]

1. Chemistry 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.

• stront(ia) + -ium 1800–10

stron•tic  (stron′tik), adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

strontium / ˈstrɒntɪəm/ noun

1. a soft silvery-white element of the alkaline earth group of metals, occurring chiefly in celestite and strontianite. Its compounds burn with a crimson flame and are used in fireworks. The radioisotope strontium-90, with a half-life of 28.1 years, is used in nuclear power sources and is a hazardous nuclear fall-out product. Symbol: Sr; atomic no: 38; atomic wt: 87.62; valency: 2; relative density: 2.54; melting pt: 769°C; boiling pt: 1384°C

Etymology: 19th Century: from New Latin, from strontian