Calcium is the element that makes bones and shells hard. Also teeth, chalk, limestone and the fur inside a kettle.
It is the most abundant metal in the human body, and almost all of it is locked up in the skeleton. Milk, cheese and leafy greens are the usual dietary sources, and vitamin D is needed to absorb it. Its symbol is Ca. Hard water is water with a lot of dissolved calcium in it, which is why kettles in some regions need descaling every few weeks.
1nouncalciumA chemical element that forms bones, teeth and shells.
“The supplement contains calcium and vitamin D.”
Latin
calx — lime, limestone
English, today
calcium
From calx + -ium. coined by Q131761 in 1808, from Latin calx (“lime, limestone”) because it occurs in limestone. by surface analysis, calc- + -ium.
Etymology from Wiktionary, CC BY-SA