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.

---

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

---

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

---

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

Explanation

Cobalt is a silvery-gray metal. It's also the name of a deep blue pigment that's made from cobalt. Cobalt, mined from the earth's crust along with copper and nickel, has a shiny appearance with a slightly bluish tint. Chemically combining cobalt with aluminum oxide results in the blue pigment that's been familiar to artists for centuries. Cobalt blue is the blue in very old Chinese blue-and-white porcelain, and it features in paintings by Monet and van Gogh. Cobalt is from the German kobold, "household goblin," a nickname miners gave arsenic-laced ore that made them sick.

Example Sentences

See Examples For:

cobalt

Deep-sea mining seeks to tap previously untouched seabed deposits of a range of commodities, including cobalt and nickel, but the fledgling industry has long been stalled by environmental concerns.

From Barron's ● Aug. 25, 2026

Cuba holds significant deposits of cobalt and nickel, which are used in the production of electronics.

From Salon ● Aug. 21, 2026

More than 70 percent of its population of 22 million lives on less than $3 a day, according to the World Bank, despite the country also having significant potential in cobalt, nickel and manganese.

From Barron's ● Aug. 16, 2026

"Our strategy is using this new carbon nanostructure to synthesize platinum cobalt intermetallic nanoparticles that can reduce precious metal content and enhance activity and stability," Wu said.

From Science Daily ● Aug. 8, 2026

Their eyes so intent on the wayward stranger who trips into their net, they were blind to the cobalt on their own backs, the moonshine fighting to pierce their comers.

From "Sula" by Toni Morrison

Related Words

• blue-green