magnesium

American  

[mag-nee-zee-uhm, -zhuhm, -shee-uhm] / mægˈni zi əm, -ʒəm, -ʃi əm /

noun

Chemistry.

1. a light, ductile, silver-white, metallic element that burns with a dazzling white light, used in lightweight alloys, flares, fireworks, in the manufacture of flashbulbs, optical mirrors, and precision instruments, and as a zinc substitute in batteries. Mg; 24.312; 12; 1.74 at 20°C.

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magnesium British  

/ mæɡˈniːzɪəm /

noun

1. a light silvery-white metallic element of the alkaline earth series that burns with an intense white flame, occurring principally in magnesite, dolomite, and carnallite: used in light structural alloys, flashbulbs, flares, and fireworks. Symbol: Mg; atomic no: 12; atomic wt: 24.3050; valency: 2; relative density: 1.738; melting pt: 650°C; boiling pt: 1090°C

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magnesium Scientific  

/ măg-nē′zē-əm /

1. A lightweight, moderately hard, silvery-white metallic element of the alkaline-earth group that burns with an intense white flame. It is an essential component of chlorophyll and is used in lightweight alloys, flash photography, and fireworks. Atomic number 12; atomic weight 24.305; melting point 649°C; boiling point 1,090°C; specific gravity 1.74 (at 20°C); valence 2.

2. See Periodic Table

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Etymology

Origin of magnesium

From New Latin, dating back to 1800–10; magnesia, -ium

Compare meaning

How does magnesium compare to similar and commonly confused words? Explore the most common comparisons:

• magnesium vs. magnesium oxide

Example Sentences

OpenEvidence doesn’t have my information, but its advice to take magnesium and creatine was consistent with suggestions from Perplexity and Claude.

From The Wall Street Journal • Apr. 4, 2026

The long-term sleep benefits of magnesium and melatonin have been scientifically proven, yet for ingredients like chamomile, any documented positive sleep impacts appear to be short-term, with placebo effects commonly occurring.

From BBC • Mar. 5, 2026

However, this research expands that understanding by examining additional minerals, including magnesium and zinc.

From Science Daily • Feb. 26, 2026

For example, China supplies 97 percent of the EU's magnesium, used in hydrogen-generating electrolysers while Turkey provides 99 percent of the bloc's boron, used in solar panels.

From Barron's • Feb. 2, 2026

All we need do is procure a sample of, say, Phobos or a comet and examine its magnesium isotopes.

From "Cosmos" by Carl Sagan