Caesium
Pronunciation : C?"si*um
Part of Speech : n.
Etymology : [NL., from L. caesius bluish gray.] (Chem.)
Definition : Defn: 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.
Source : Webster's Unabridged Dictionary, 1913