caesium
/ˈsiːzi.əm/ noun
Forms cæsium cesium
- noun The chemical element (symbol Cs) with an atomic number of 55. It is a soft, gold-colored, highly reactive alkali metal.
Synonyms
Etymology
From Latin caesius (“sky-blue”), in reference to the radiation spectra, + -ium.
Webster’s 1913
- noun A rare alkaline metal found in mineral water; --so called from the two characteristic blue lines in its spectrum. It was the first element discovered by spectrum analysis, and is the most strongly basic and electro-positive substance known. Symbol Cs. Atomic weight 132.6.
Etymology [NL., from L. caesius bluish gray.]
Sources: Wiktionary · WordNet 3.0 · Webster’s 1913 — from the Wiktionary entry “caesium”, CC BY-SA 4.0. Details