from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A light, silvery-white, moderately hard metallic element that in ribbon or powder form burns with a brilliant white flame. Obtained chiefly from magnesite and dolomite, it is used in structural alloys, pyrotechnics, flash photography, and incendiary bombs. Atomic number 12; atomic weight 24.305; melting point 650°C; boiling point 1,090°C; specific gravity 1.738 (at 20°C); valence 2. cross-reference: Periodic Table.

from The Century Dictionary.

  • noun Manganese.
  • noun Chemical symbol, Mg; atomic weight, 24.4. The metallic base of the widely distributed alkaline earth magnenesia, which in various combinations, and especially in the form of the double carbonate of lime and magnesia, is one of the most abundant of the materials which make up the earth's crust.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Chem.) A light silver-white metallic element of atomic number 12, malleable and ductile, quite permanent in dry air but tarnishing in moist air. It burns, forming (the oxide) magnesia, with the production of a blinding light (the so-called magnesium light) which is used in signaling, in pyrotechny, or in photography where a strong actinic illuminant is required. Its compounds occur abundantly, as in dolomite, talc, meerschaum, etc. Symbol Mg. Atomic weight, 24.305. Specific gravity, 1.75.
  • noun (Chem.) Same as Epsom salts.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A light, flammable, silvery metal, and a chemical element (symbol Mg) with an atomic number of 12.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a light silver-white ductile bivalent metallic element; in pure form it burns with brilliant white flame; occurs naturally only in combination (as in magnesite and dolomite and carnallite and spinel and olivine)


from The American Heritage® Dictionary of the English Language, 4th Edition

[From magnesia.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From New Latin magnēsium, from Magnēsia (“region in Thessaly”) +‎ -ium.



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  • Mg.

    December 16, 2007