calcium

American  

[kal-see-uhm] / ˈkæl si əm /

noun

Chemistry, Biology.

1. a silver-white divalent metal, occurring combined in limestone, chalk, gypsum, etc., occurring also in vertebrates and other animals, as a component of bone, skeletal mass, shell, etc., and as a necessary element in nerve conduction, heartbeat, muscle contraction, and many other physiological functions. Ca; 40.08; 20; 1.55 at 20°C.

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calcium British  

/ ˈkælsɪəm /

noun

1. a malleable silvery-white metallic element of the alkaline earth group; the fifth most abundant element in the earth's crust (3.6 per cent), occurring esp as forms of calcium carbonate. It is an essential constituent of bones and teeth and is used as a deoxidizer in steel. Symbol: Ca; atomic no: 20; atomic wt: 40.078; valency: 2; relative density: 1.55; melting pt: 842±2°C; boiling pt: 1494°C

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calcium Scientific  

/ kăl′sē-əm /

1. A silvery-white, moderately hard metallic element of the alkaline-earth group that occurs in limestone and gypsum. It is a basic component of leaves, bones, teeth, and shells, and is essential for the normal growth and development of most animals and plants. Calcium is used to make plaster, cement, and alloys. Atomic number 20; atomic weight 40.08; melting point 842 to 848°C; boiling point 1,487°C; specific gravity 1.55; valence 2.

2. See Periodic Table

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Etymology

Origin of calcium

First recorded in 1800–10; calc- + -ium

Example Sentences

Genetic sequencing was used to identify the microorganisms present, while gene expression studies helped reveal potential biological functions connected to calcium carbonate formation.

From Science Daily • May 31, 2026

The report didn’t include specific metrics such as a calcium score, plaque description or ejection fraction, which doctors typically expect.

From The Wall Street Journal • May 31, 2026

"The ocean is especially rich in these partnerships, and the toadfish-vibrio symbiosis potentially linked to calcium carbonate production is a striking new example."

From Science Daily • May 31, 2026

The procedure treats a condition in which the heart’s aortic valve narrows due to calcium buildup, making it harder to pump blood.

From The Wall Street Journal • Apr. 24, 2026

For a while she simply stands there before tending to the shampooing of her hair, the soaping of her softening, slightly shrinking fifty-three-year-old body, which she must fortify each morning with calcium pills.

From "The Namesake" by Jhumpa Lahiri