/ ˈkəʊbɔːlt; NAmE ˈkoʊ-/ noun [ U ]
1.
( symb Co ) a chemical element. Cobalt is a hard silver-white metal, often mixed with other metals and used to give a deep blue-green colour to glass.
2.
(also ˌcobalt ˈblue ) a deep blue-green colour
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WORD ORIGIN
late 17th cent.: from German Kobalt imp, demon (from the belief that cobalt was harmful to the ores with which it occurred).