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

Electrolytes are electrically charged minerals like sodium, potassium and magnesium that are important for muscle function and hydration balance, and they’re found in many different kinds of food.

From MarketWatch ● Jul. 11, 2026

Scientists also recorded higher levels of other firework-related pollutants, including fine particulate matter and sulfate and potassium ions.

From Science Daily ● Jul. 4, 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

A diet packed with fruit and vegetables, rather than going all in on ultra-processed foods, will contain potassium, which can counteract some of the impact of salt.

From BBC ● May 15, 2026

“Sorry, it’s all I’ve got. Anyway, potassium chlorate is unstable under heat and pressure. It's too dangerous for rocket fuel. What do your parents think about the BCMA?”

From "October Sky" by Homer Hickam