potassium

American

[puh-tas-ee-uhm] / pəˈtæs i əm /

noun

Chemistry.

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

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 /

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.
See Periodic Table

Other Word Forms

potassic

adjective

Etymology

Origin of potassium

From New Latin, dating back to 1800–10; see origin at 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.

Potassium nitrate was linked to a 13% increased risk of overall cancer and a 22% higher risk of breast cancer.

From Science Daily • Jan. 27, 2026

Potassium chloride looks the same as sodium chloride and tastes very similar.

From Salon • Jan. 30, 2024

Potassium iodide, or KI, offers specific protection against one kind exposure.

From Seattle Times • Oct. 13, 2022

Potassium iodide is used to saturate a person’s thyroid with iodine so that radioactive iodine inhaled or ingested after exposure will not be retained by the gland.

From New York Times • Oct. 12, 2022

"Potassium chlorate!" as the shells go womp-womp-womp and everybody goes oooooooh.

From "Freak The Mighty" by Rodman Philbrick

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