sodium

American  

[soh-dee-uhm] / ˈsoʊ di əm /

noun

• sodiums
  plural

1. Chemistry. a soft, silver-white, metallic element that oxidizes rapidly in moist air, occurring in nature only in the combined state, and used in the synthesis of sodium peroxide, sodium cyanide, and tetraethyllead: a necessary element in the body for the maintenance of normal fluid balance and other physiological functions. Na; 22.9898; 11; 0.97 at 20°C.

2. Medicine/Medical, Pharmacology. any salt of sodium, as sodium chloride or sodium bicarbonate, present in or added to foods or beverages as a seasoning or preservative and used in many pharmaceutical products as an antacid, anticoagulant, or other agent.

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sodium British  

/ ˈsəʊdɪəm /

noun

1. 1. a very reactive soft silvery-white element of the alkali metal group occurring principally in common salt, Chile saltpetre, and cryolite. Sodium and potassium ions maintain the essential electrolytic balance in living cells. It is used in the production of chemicals, in metallurgy, and, alloyed with potassium, as a cooling medium in nuclear reactors. Symbol: Na; atomic no: 11; atomic wt: 22.989768; valency: 1; relative density: 0.971; melting pt: 97.81±0.03°C; boiling pt: 892.9°C

   2. ( as modifier )

      sodium light

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sodium Scientific  

/ sō′dē-əm /

1. A soft, lightweight, silvery-white metallic element of the alkali group that reacts explosively with water. It is the most abundant alkali metal on Earth, occurring especially in common salt. Sodium is very malleable, and its compounds have many important uses in industry. Atomic number 11; atomic weight 22.99; melting point 97.8°C; boiling point 892°C; specific gravity 0.971; valence 1.

2. See Periodic Table

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Other Word Forms

Noun Inflected Forms

• sodiums
  plural

Etymology

Origin of sodium

From New Latin, dating back to 1800–10; see origin at soda, -ium

Compare meaning

How does sodium compare to similar and commonly confused words? Explore the most common comparisons:

• potassium vs. sodium

Explanation

Sodium is a chemical element, a soft silver-colored metal. When it's combined with chlorine, sodium turns into table salt. If you have high blood pressure, you doctor might tell you to cut back on sodium in your diet. The pure form of sodium is bright and silvery, and soft enough that you can cut it with a knife. Combined with other elements, sodium is present in many common things, including glass, paper, fertilizer, baking soda, and the salt in the shaker on your table. The first scientist to isolate sodium, Humphry Davy, did it using caustic soda, or sodium hydroxide, and coined the new element's name from soda.

Example Sentences

See Examples For:

sodium

That said, there are cases of endurance athletes drinking excessive fluids, resulting in life-threatening conditions like hyponatremia, when blood sodium levels drop too low.

From The Wall Street Journal ● Aug. 27, 2026

The woman was prescribed sodium valproate in the 90s for seizures, and was taking it during two of her four pregnancies.

From BBC ● Aug. 11, 2026

A recent report from Morgan Stanley projects that within a decade, more than a third of all batteries produced in the world will use sodium, not lithium.

From The Wall Street Journal ● Aug. 7, 2026

"The sodium likely originated from the lunar soil, whereas the lithium could come from the rocket itself," the post continued, adding that the team would offer more details following fuller analysis.

From Barron's ● Aug. 5, 2026

I could put on an interesting outfit, crack a joke, and talk about sodium content in kids’ meals without being totally boring.

From "Becoming" by Michelle Obama