magnesium

American  

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

noun

Chemistry.

magnesiums plural

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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Other Word Forms

Noun Inflected Forms

• magnesiums
  plural

Etymology

Origin of magnesium

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

Compare meaning

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

• magnesium vs. magnesium oxide

Explanation

Magnesium is a shiny metallic chemical element, and it's also a mineral that humans and other organisms need to be healthy. In nature, magnesium is only found combined with other elements, never on its own. When scientists isolate magnesium from these compounds, it looks silvery-white. Magnesium is an excellent conductor of electricity, and it burns brightly. It's used to make fireworks and flares, and it's often combined with aluminum and zinc to make lightweight metal alloys. Ionized magnesium is necessary for our bodies to function properly: It is involved in over 300 biochemical reactions in the human body. Many people take supplements containing magnesium compounds.

Example Sentences

Electrolytes are electrically charged minerals like sodium, potassium and magnesium that are important for muscle function and hydration balance, and they’re found in many different kinds of food.

From MarketWatch • Jul. 11, 2026

Without realising it, I had accumulated several pouches of creatine, vitamin D, magnesium, collagen, an all-in-one green supplement, and some tablets designed to help with the ups and downs of perimenopause.

From BBC • Jun. 20, 2026

Investigations showed the solution was missing magnesium, which caused embryos to stop developing, degrade, or die.

From Barron's • Jun. 5, 2026

It also removed magnesium, one of the most common contaminants in lithium brines, through a chemical precipitation step that separates the unwanted material.

From Science Daily • May 23, 2026

But Franklin’s measurements suggested that magnesium could not be at the center.

From "The Gene" by Siddhartha Mukherjee