Real Dictionary

cobalt
uncountable noun: Cobalt is a hard silvery-white metal which is used to harden steel and for producing a blue dye.

cobalt in American English
a hard, lustrous, steel-gray, ductile, metallic chemical element, found in various ores: it is used in the preparation of magnetic, wear-resistant, and high-strength alloys: its compounds are used in the production of inks, paints, and varnishes: symbol,
noun: a silver-white metallic element with a faint pinkish tinge, occurring in compounds whose silicates afford important blue coloring substances for ceramics; at. wt.: 58.933; at. no.: 27; sp. gr.: 8.9 at 20°C

cobalt in British English
noun: a brittle hard silvery-white element that is a ferromagnetic metal: occurs principally in cobaltite and smaltite and is widely used in alloys. The radioisotope cobalt-60, with a half-life of 5.3 years, is used in radiotherapy and as a tracer. Symbol: Co;