Definition of cobalt in English:



mass noun
  • 1

    (also Co)
    The chemical element of atomic number 27, a hard silvery-white magnetic metal.

    • ‘This packing arrangement is also observed for many metals, including rubidium, osmium, cobalt, zinc, and cadmium.’
    • ‘Besides gold and diamonds, the area is rich in copper, uranium, palladium and cobalt, as well as coltan ore.’
    • ‘The slow growth rate is thought to enhance the absorption of heavy metals like copper and cobalt from sea water.’
    • ‘We are already exporting gold and we have substantial resources of silver, uranium, nickel and cobalt, the deposits of which need further investigation.’
    • ‘They blended and heated plutonium with gallium and cobalt and then slowly cooled the molten mixture.’
    1. 1.1
      short for cobalt blue
      as modifier ‘a cobalt sky’
      short for cobalt blue
      • ‘He muttered something in angry fluent French, as he tilted his head back and looked up at the star-dusted cobalt sky.’
      • ‘It was February with cobalt skies, snappy air, and a fresh blanket of snow.’
      • ‘This past week in the forest park, the fiery foliage set against cobalt skies was a sight to behold.’
      • ‘I got out my sketch book and showed him some of the paintings I'd done of lizard head spires piercing skies of cobalt and turpentine.’
      • ‘Above, the serrated edge of the granite ridge cuts through the cobalt sky.’
      • ‘His gaze caught mine and for a second his cobalt eyes were a mirror for the sun.’
      • ‘Not only were his eyes lacking their normal cobalt hue and his pupils disturbingly restricted but now his eyes were blood shot as well.’
      • ‘The softly tailored look is also very much in this season with glowing colours such as cobalt and rich greens coupled with subtly shaded creams and browns.’
      • ‘And then came the third line, a collection in shades of aquamarine, cobalt, ethereal blue, sky blue, and dream blue.’
      • ‘The cloudless sky was the color of cobalt, so blue he felt he could breathe it in and out and become a part of it.’
      • ‘Other houses' bathrooms are characterised by bright cobalt blues or pearl whites.’
      • ‘On a walk through the five-acre garden you encounter great bushes of Blue Bonnet, whose huge flower heads vary from powder blue to cobalt.’
      • ‘It was of dark cobalt, running to purple, and had golden thread work all along the hem and sleeves.’
      • ‘He lifted up his cobalt eyes to his friend for only a split second and then glanced back down.’
      • ‘Side plates at each place setting are coloured a brilliant turquoise or patterned in cobalt or shaped like river boats.’
      • ‘The purple on his surcoat made his striking cobalt eyes seem deep violet.’
      • ‘What snatches of blue sky she could see were deepening from azure to cobalt and she thought she saw the first star twinkling already.’
      • ‘He left a tip and walked outside to his cobalt truck, driving away only a few moments later.’
      • ‘He took her hand and kissed it, his cobalt eyes twinkling.’
      • ‘His stormy cobalt eyes glanced down at her and he sighed again.’

Cobalt is chiefly obtained as a by-product from nickel and copper ores. It is a transition metal similar in many respects to nickel and is mainly used as a component of magnetic alloys and those designed for use at high temperatures


Late 17th century from German Kobalt ‘imp, demon’ (because the presence of cobalt-bearing ore made it more difficult to extract silver, and miners believed that it was harmful to the silver ore with which it occurred).



/ˈkəʊbɔːlt/ /ˈkəʊbɒlt/