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

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

The scientists first compared several metal nanocatalysts, including silver, cobalt, palladium, and platinum.

From Science Daily ● Aug. 10, 2026

"Traditionally, there would be a tradeoff between size and stability, but with the ordered carbon nanochannel host, platinum cobalt nanoparticles can be confined and remain stable at very small particle size even at high temperatures."

From Science Daily ● Aug. 8, 2026

They were cobalt blue, purple from manganese, yellow from copper, red, and a green which was also got from copper.

From "The Once and Future King" by T. H. White

Random Word

Spin the wheel and learn a new word!

---

Related Words

• blue-green

---