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[koh-bawlt] /ˈkoʊ bɔlt/
a silver-white metallic element with a faint pinkish tinge, occurring in compounds whose silicates afford important blue coloring substances for ceramics. Symbol: Co; atomic weight: 58.933; atomic number: 27; specific gravity: 8.9 at 20°C.
1675-85; < German Kobalt, variant of Kobold kobold Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for cobalt
  • Some wires, made of cobalt oxide and gold, become the negative poles of the battery.
  • Shades of a cobalt blue fresco can be found above the stepped altar.
  • Beside them were battered cobalt blue trucks-the ones used to whisk away prisoners and detainees.
  • When a current runs through an electrode, phosphate and cobalt in the water form a thin film on that electrode.
  • As cobalt decays, it becomes less effective, so you have to monitor that.
  • On top of the electrolyte they added a virus modified to produce a protein coat that collects molecules of cobalt oxide.
  • Yellow jellyfish and red octopuses jet through cobalt waters.
  • Sulfurous fractions are mixed with hydrogen and a cobalt-molybdenum catalyst, yielding hydrogen sulfide.
  • But they also found that the enhanced acidity led to dissolution of metals such as uranium, cobalt, cadmium and iron.
  • The steel used in the pipes, however, is usually alloyed with cobalt to make it stronger.
British Dictionary definitions for cobalt


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
Word Origin
C17: German Kobalt, from Middle High German kobolt goblin; from the miners' belief that malicious goblins placed it in the silver ore
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for cobalt

1680s, from German kobold "household goblin," Harz Mountains silver miners' term for rock laced with arsenic and sulfur (so called because it degraded the ore and made the miners ill), from Middle High German kobe "hut, shed" + *holt "goblin," from hold "gracious, friendly," a euphemistic word for a troublesome being. The metallic element was extracted from this rock. It was known to Paracelsus, but discovery is usually credited to the Swede George Brandt (1733), who gave it the name. Extended to a blue color 1835 (a mineral containing it had been used as a blue coloring for glass since 16c.). Cf. nickel.

Online Etymology Dictionary, © 2010 Douglas Harper
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cobalt in Medicine

cobalt co·balt (kō'bôlt')
Symbol Co
A metallic element, used chiefly for magnetic and high-temperature alloys and in the form of its salts for blue glass and ceramic pigments. Atomic number 27; atomic weight 58.9332; melting point 1,495°C; boiling point 2,930°C; specific gravity 8.9; valence 2, 3.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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cobalt in Science
Symbol Co
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. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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