sodium

The word “sodium” means a soft, silvery, highly reactive chemical element (symbol Na) that never occurs alone in nature. In plain terms, a chemical element found combined with other substances, most familiarly in table salt.

“Sodium” is pronounced SOH-deerm (/ˈsoʊ.di.əm/ in IPA).

Here is “sodium” used in a sentence: “Table salt is a compound of sodium and chlorine.”

Words with a similar meaning to “sodium” include natrium.

“Sodium” is a noun.

The word “sodium” dates back to around 1808. Coined in 1808 by chemist Humphry Davy, from "soda" + the element-naming suffix -ium.

“Sodium” is a fairly common word in modern English.

Sodium is a single chemical element (symbol Na), while table salt is a compound called sodium chloride that combines sodium with chlorine. Because sodium never occurs alone in nature, the sodium in food is almost always bound to other elements, most often as salt.

Nutrition labels report sodium because it is the part of salt linked to health measures such as blood pressure. Since salt is only about 40 percent sodium by weight, the sodium figure on a label is lower than the total amount of salt in the food.

The symbol "Na" comes from natrium, the Latin-based name for the element, which is why the abbreviation does not match the English spelling. For this reason sodium is still called natrium in some scientific and European contexts.

Sodium is a highly reactive element, so it readily combines with other substances rather than existing in pure form. In nature it is always locked into compounds, such as sodium chloride in seawater and rock salt.