English Reference

Word

cobalt

US/ˈkoʊˌbɔɫt/

UK/kˈəʊbɒlt/

Definitions

01the chemical element

C1 · Science

n. a hard, silver-grey metal used in batteries and to make strong steel.

n. a hard, lustrous, silver-grey metallic element used in high-strength alloys and lithium-ion batteries. Uncountable in its elemental sense.

“Cobalt is an essential component in the batteries used for electric cars.”

“The global demand for cobalt has surged due to its critical role in the production of rechargeable batteries for portable electronics.”

Technical

Synonyms

Co

02the colour

B2

n. a deep, bright blue colour.

n. a deep, vivid blue pigment or colour, traditionally derived from cobalt salts.

“The artist used a touch of cobalt to paint the evening sky.”

“The ceramicist applied a cobalt glaze to the porcelain, which turned a brilliant blue after being fired in the kiln.”

Synonyms

cobalt bluedeep blue

03deep blue

B2

adj. having a deep, bright blue colour.

adj. denoting a specific shade of deep, intense blue. Often used to describe fashion, decor, or natural features.

“She wore a cobalt dress that matched the colour of her eyes.”

“The interior designer recommended cobalt tiles for the bathroom to create a bold, modern aesthetic.”

Synonyms

vivid bluebright blue

Real-World Examples

“Although the research focuses on cobalt, the same approach could be applied to other critical materials that support battery production and clean energy technologies.”
ScienceDaily · 20 Jun 2026
“They also carefully controlled and monitored the temperature so that it remained above the melting point for cobalt but below the temperature of grain growth.”
ScienceDaily · 4 Aug 2026

Etymology

From German Kobalt, formerly also Kobald, ‑olt, ‑old, ‑elt, ‑el, apparently the same word as Kobold (“goblin”), from Middle High German, which became also a Harz Mountains silver miners’ term for rock laced with arsenic and sulfur, so called because it degraded the ore and made the miners ill. Doublet of kobold.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry

Level
C1 · Advanced
Frequency
Frequent
Updated

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English Reference