cesium

ce·si·um also cae·si·um   (sē'zē-əm)    n.   Symbol Cs A soft, silvery-white ductile metal, liquid at room temperature, the most electropositive and alkaline of the elements, used in photoelectric cells and to catalyze hydrogenation of some organic compounds. Atomic number 55; atomic weight 132.905; melting point 28.5°C; boiling point 690°C; specific gravity 1.87; valence 1. See Table at element. [From Latin caesius, bluish gray (from its blue spectral lines).]

cesium 

Main Entry: ce·si·um
Variant: or chiefly British cae·si·um /'sE-zE-&m/
Function: noun
: a silver-white softductile element of the alkali metal group that is the most electropositive element known and that is used especially in photoelectric cells —symbol Cs; —see ELEMENT table

cesium ce·si·um or cae·si·um (sē'zē-əm)
n.
Symbol Cs
A soft ductile metal, liquid at room temperature, the most electropositive and alkaline of the elements, used in photoelectric cells. Atomic number 55; atomic weight 132.905; melting point 28.4°C; boiling point 671°C; specific gravity 1.87; valence 1.

cesium   (sē'zē-əm)  Pronunciation Key  Symbol Cs A soft, ductile, silvery-white element of the alkali group. It is liquid at room temperature and is the most reactive of all metals. Cesium is used to make photoelectric cells, electron tubes, and atomic clocks. Atomic number 55; atomic weight 132.905; melting point 28.5°C; boiling point 690°C; specific gravity 1.87; valence 1. See Periodic Table.