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

More interesting for Bott than the climate benefit is the way calcium carbonate makes water more alkaline.

From The Wall Street Journal • May 14, 2026

The procedure is designed to treat severe aortic stenosis, in which calcium buildup narrows the opening of the aortic valve.

From The Wall Street Journal • Apr. 24, 2026

The team placed a small dolomite crystal in a solution containing calcium and magnesium.

From Science Daily • Apr. 20, 2026

In February 2025, Kayan was admitted to hospital in Sheffield with high levels of calcium and reduced kidney function.

From BBC • Apr. 16, 2026

I feel lighter, as if I’m shedding matter, losing molecules, calcium from my bones, cells from my blood; as if I’m shrinking, as if I’m filling with cold air, or gently falling snow.

From "Cat's Eye" by Margaret Atwood