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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.

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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

Other Word Forms

  • potassic adjective

Etymology

Origin of potassium

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

Compare meaning

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Vocabulary lists containing potassium

Nutrition - Middle School

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Nutrition - High School

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Nutrition and Digestion - High School

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

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

From Salon • Apr. 8, 2026

"Urine does naturally contain all of the nutrients that plants need such as nitrogen, phosphorus and potassium, but it also contains a variety of contaminants," explained Olivia Wilson, NPK Recovery's research and development scientist.

From BBC • Apr. 2, 2026

Consuming too much sodium and not enough potassium are key contributors to elevated blood pressure.

From Science Daily • Mar. 31, 2026

The medications activate potassium channels, which relax pericytes and allow previously constricted blood vessels to widen.

From Science Daily • Mar. 4, 2026

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

From "Meltdown" by Deirdre Langeland

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.