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

Chinese producers use American sulfur to manufacture phosphate fertilizers, which supply phosphorus—one of the three primary plant nutrients along with nitrogen and potassium.

From The Wall Street Journal ● Aug. 28, 2026

"Salt particles -- specifically sodium chloride and potassium chloride -- are most often used" as cloud-seeding agents, said Adnan Yarmohammed, one of the Emirati officials in charge of sharing his country's experience.

From Barron's ● Aug. 12, 2026

Rather than considering sodium and potassium separately, recommendations should address how the two nutrients work together.

From Science Daily ● Jul. 31, 2026

Average sodium consumption continues to exceed recommended levels, while potassium intake is frequently "far below optimal levels in both developed and developing nations," according to the authors.

From Science Daily ● Jul. 31, 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