What does cobalt mean?
Cobalt is a hard, lustrous, silver-grey metallic element, symbol Co and atomic number 27, prized for its heat resistance and magnetic properties. It is essential in superalloys for jet engines, permanent magnets, and — most prominently today — the cathodes of lithium-ion rechargeable batteries that power phones and electric vehicles. By extension, cobalt names a strikingly deep, vivid blue, first made famous by cobalt-oxide pigments in Chinese porcelain and European glassware, and now a staple of artists' palettes as 'cobalt blue'. The word entered English in the seventeenth century from German Kobalt, itself derived from Kobold, meaning goblin: Saxon miners, frustrated by ores that looked like silver but yielded poisonous arsenic fumes when smelted, believed mountain spirits were sabotaging them. Few elements carry such an evocative folklore alongside such modern industrial weight.
A hard, brittle, silver-grey magnetic metallic element with symbol Co and atomic number 27, used chiefly in alloys, magnets, catalysts, and battery cathodes.
"The refinery processes ore rich in copper and cobalt."
Usually uncountable when denoting the substance; takes the indefinite article only in scientific contexts discussing individual atoms or isotopes (e.g. 'a cobalt-60 source').
A deep, brilliant blue colour resembling that of cobalt pigments; also, a pigment producing this colour.
"The tiles were glazed in a luminous cobalt against cream stonework."
Typically used attributively ('cobalt blue', 'a cobalt suit'); as a standalone count noun it refers to a shade on an artist's palette.
Rarely pluralized; the plural appears only when referring to multiple shades of cobalt blue or to different isotopes/forms of the element in technical writing.
"Her palette held three distinct cobalts, each ground from a different pigment."
Cobalt is literally named after goblins — German miners blamed mischievous 'kobolds' for the deceptive ore that spewed toxic fumes when they tried to smelt it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cobalt
The word cobalt derives from German Kobalt, used in sixteenth-century mining circles for the troublesome ore later found to contain cobalt and arsenic. German Kobalt comes from Kobold, a house spirit or goblin in German folklore, reflecting the miners' superstition that such sprites had corrupted the ore to deceive them. The element was isolated and identified by Swedish chemist Georg Brandt around 1735, making it the first metal discovered since antiquity whose isolation is well documented. English adopted the term in the early seventeenth century, initially in reference to the blue pigment before the metal itself was clearly characterized.
Related word forms
How cobalt is actually used
As an uncountable mass noun when referring to the metal ('extracted cobalt'), but countable when referring to shades of colour ('a cobalt'). The colour sense almost always appears attributively ('a cobalt dress', 'cobalt glass') and carries connotations of intensity, clarity, and artistic refinement.