caesium

• POS: Noun
• HYPHEN: cae=si=um

CIDE DICTIONARY

caesium, n. [NL., from L. caesius bluish gray.].

 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 number 55. Atomic weight 132.6.  [1913 Webster]

OXFORD DICTIONARY

caesium, n. (US cesium) a soft silver-white element of the alkali metal group, occurring naturally in a number of minerals, and used in photoelectric cells.

Idiom

caesium clock an atomic clock that uses caesium.

Usage

Symb.: Cs.

Etymology

as CAESIOUS (from its spectrum lines)