sodium

American  

[soh-dee-uhm] / ˈsoʊ di əm /

noun

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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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

Sodium phosphate is used to preserve moisture and enhance flavor in processed foods, while carrageenan is added to thicken and stabilize products like meats.

From Los Angeles Times • Jan. 28, 2026

Sodium nitrite was associated with a 32% higher risk of prostate cancer.

From Science Daily • Jan. 27, 2026

Sodium is naturally found in food, and people who eat a Western diet tend to add quite a bit extra to their meals in the form of table salt too.

From Slate • Aug. 17, 2025

Sodium citrate — a food-safe salt that binds the cheese and cream together into that iconic velvety texture Kraft first developed back in the 1910s.

From Salon • Jul. 6, 2025

Spectrum of Carbon Sodium and Lithium 48 9.

From Colour Measurement and Mixture by Abney, W. de W.