calcium

noun

cal·​ci·​um ˈkal-sē-əm 

often attributive

: a metallic chemical element of the alkaline-earth group that occurs naturally only in combination and is essential to cellular functions in all known organisms see Chemical Elements Table

Examples of calcium in a Sentence

Her doctor said she should eat more foods that are high in calcium, such as milk and cheese.

Recent Examples on the Web

According to Jonathan Rasouli, MD, a neurosurgeon at Northwell Health’s Staten Island University Hospital, fatty dairy products contain nutrients such as vitamin K2, calcium, and certain fatty acids that may support brain health. —Julia Ries Wexler, Health, 9 Jan. 2026

One of their first steps was the elective CT scan to look for any calcium buildup in the arteries around the heart. —Nicole Villalpando, Austin American Statesman, 8 Jan. 2026

How Magnesium May Lower Blood Pressure One of the key functions of magnesium is its ability to act as a natural calcium antagonist. —Morgan Pearson, Verywell Health, 8 Jan. 2026

In the study, Yale School of Medicine, or YSM, researchers discovered elevated GLO1 levels in the brains of animals with excessive levels of cellular calcium, finding that the brain increased GLO1 expression as a protective mechanism to mitigate the effects of the calcium dysregulation. —Isabella Backman, Hartford Courant, 6 Jan. 2026

Word History

Etymology

New Latin, from Latin calc-, calx lime

First Known Use

1808, in the meaning defined above

Phrases Containing calcium

• calcium carbide
• calcium carbonate
• calcium channel blocker
• calcium chloride
• calcium citrate
• calcium cyanamide
• calcium gluconate
• calcium hydroxide
• calcium hypochlorite
• calcium oxalate
• calcium oxide
• calcium phosphate
• calcium silicate
• calcium sulfate

Rhymes for calcium

• dicalcium
• tricalcium

Kids Definition

calcium

noun

cal·​ci·​um ˈkal-sē-əm 

: a silver-white soft metallic element that is found only in combination with other elements (as in limestone) and is one of the necessary elements making up the bodies of most plants and animals see element

Etymology

derived from Latin calc-, calx "lime" — related to calculate, chalk

Medical Definition

calcium

noun

cal·​ci·​um ˈkal-sē-əm 

often attributive

: a silver-white bivalent metallic element that is an alkaline earth metal, occurs only in combination, and is an essential constituent of most plants and animals

—symbol Ca see Chemical Elements Table