potassium

American  

[puh-tas-ee-uhm] / pəˈtæs i əm /

noun

Chemistry.

1. a silvery-white metallic element that oxidizes rapidly in the air and whose compounds are used as fertilizer and in special hard glasses. K; 39.102; 19; 0.86 at 20°C.

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potassium British  

/ pəˈtæsɪəm /

noun

1. a light silvery element of the alkali metal group that is highly reactive and rapidly oxidizes in air; occurs principally in carnallite and sylvite. It is used when alloyed with sodium as a cooling medium in nuclear reactors and its compounds are widely used, esp in fertilizers. Symbol: K; atomic no: 19; atomic wt: 39.0983; valency: 1; relative density: 0.862; melting pt: 63.71°C; boiling pt: 759°C

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potassium Scientific  

/ pə-tăs′ē-əm /

1. A soft, highly reactive, silvery-white metallic element of the alkali group occurring in nature only in compounds. It is essential for the growth of plants and is used especially in fertilizers and soaps. Atomic number 19; atomic weight 39.098; melting point 63.65°C; boiling point 774°C; specific gravity 0.862; valence 1.

2. See Periodic Table

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Other Word Forms

• potassic
  adjective

Etymology

Origin of potassium

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

Compare meaning

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

• potassium vs. sodium
• potassium vs. potassium chloride

Example Sentences

See Examples For:

potassium

For example, dehydration often causes a severe drop in blood pressure and imbalances in electrolytes like sodium and potassium.

From MarketWatch ● Jul. 12, 2026

And she includes two pickles, which are packed with electrolytes from the sodium in the brine and traces of potassium.

From The Wall Street Journal ● Jul. 3, 2026

When exposed to air, the potassium hydroxide inside the beads reacts with CO2, producing hydrogen carbonate, a salt of carbonic acid.

From Science Daily ● Jun. 11, 2026

To maximize production, those crops need three main nutrients: nitrogen, phosphate and potassium.

From Salon ● Apr. 8, 2026

Cesium 137 behaves like potassium and is used throughout the body, winding up mostly in muscle tissue.

From "Meltdown" by Deirdre Langeland