cesium

or cae·si·um

[ see-zee-uhm ]

noun
  1. a rare, highly reactive, soft, metallic element of the alkali metal group, used chiefly in photoelectric cells. Symbol: Cs; atomic weight: 132.905; atomic number:55;specific gravity: 1.9 at 20°C; melts at 28.5°C.

Origin of cesium

1
1930–35; <New Latin, special use of Latin caesium, neuter of caesius bluish-grey; see -ium

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British Dictionary definitions for cesium

cesium

/ (ˈsiːzɪəm) /


noun
  1. the usual US spelling of caesium

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for cesium

cesium

[ zē-əm ]


Cs
  1. 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.

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