n. A metallic chemical element (symbol Cs) with an atomic number of 55.
the GNU version of the Collaborative International Dictionary of English
n. 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.
The Century Dictionary and Cyclopedia
n. Chemical symbol, Cs; atomic weight, 132.8. A rare metal discovered by Bunsen and Kirchhoff by spectrum analysis in the saline waters of Dürkheim in Germany, and subsequently in other mineral waters.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal
Word Usage
"Their light is emitted by vaporised alkali metals such as caesium or potassium. reports they have "mass-to-power ratios that far exceed what is possible with today's other laser systems"."