cobalt

American  

[koh-bawlt] / ˈkoʊ bɔlt /

noun

1. a silver-white metallic element with a faint pinkish tinge, occurring in compounds whose silicates afford important blue coloring substances for ceramics. Co; 58.933; 27; 8.9 at 20°C.

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cobalt British  

/ ˈkəʊbɔːlt /

noun

1. 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; atomic no: 27; atomic wt: 58.93320; valency: 2 or 3; relative density: 8.9; melting pt: 1495°C; boiling pt: 2928°C

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cobalt Scientific  

/ kō′bôlt′ /

1. A silvery-white, hard, brittle metallic element that occurs widely in metal ores. It is used to make magnetic alloys, heat-resistant alloys, and blue pigment for ceramics and glass. Atomic number 27; atomic weight 58.9332; melting point 1,495°C; boiling point 2,900°C; specific gravity 8.9; valence 2, 3.

2. See Periodic Table

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Etymology

Origin of cobalt

1675–85; < German Kobalt, variant of Kobold kobold

Compare meaning

How does cobalt compare to similar and commonly confused words? Explore the most common comparisons:

• cobalt vs. royal blue

Example Sentences

China currently dominates the global supply of lithium and cobalt, both of which are needed in batteries.

From Barron's • Mar. 28, 2026

China currently dominates the global supply of lithium and cobalt, both of which are needed in batteries.

From Barron's • Mar. 28, 2026

Other companies invested tens of billions of dollars in building plants in the U.S. to make lithium-ion batteries with expensive nickel and cobalt inside.

From The Wall Street Journal • Mar. 24, 2026

Zimbabwe has some of Africa's largest lithium reserves, as well as chromium, cobalt and rare earth minerals.

From BBC • Mar. 14, 2026

A few bright stars lingered in the cobalt sky.

From "A Dance with Dragons" by George R. R. Martin

Related Words

• blue-green