Noun mg has 2 senses
  1. milligram, mg - one thousandth (1/1,000) gram
    --1 is a kind of metric weight unit, weight unit
    --1 is a part of grain, metric grain
    --1 has parts: microgram, mcg
  2. magnesium, Mg, atomic number 12 - 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)
    --2 is a kind of metallic element, metal
    --2 is a substance of
     carnallite; dolomite; magnesite; olivine; periclase, magnesia, magnesium oxide; spinel
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