Potassium Definition

A soft, silver-white, waxlike metallic chemical element, one of the alkali metals, that oxidizes rapidly when exposed to air: it occurs abundantly in nature in the form of its salts, which are used in fertilizers, glass, etc.: symbol, K; at. no. 19
Webster's New World

A soft, waxy, silvery reactive metal that is never found unbound in nature; an element (symbol K) with an atomic number of 19 and atomic weight of 39.0983. The symbol is derived from the Latin kalium.


(physics) The major stable isotope of potassium, 3919K, having nineteen protons and twenty neutrons; it amounts to over 93% of the element in nature.


(physics) A naturally-occurring radioactive isotope of potassium, 4019K, having nineteen protons and twenty-one neutrons, and a half-life of 1.3 billion years; it is the chief source of natural radioactivity in living tissue.


(physics) An artificially produced radioactive isotope of potassium, 4219K, having a half-life of 12.4 hours; used in medicine as a tracer.

  • k
  • atomic number 19

Origin of Potassium

  • From earlier potass potash (from which it was first obtained) from French potasse from Dutch potas pot pot (from Middle Dutch) (Old English pott) as ash (from Middle Dutch asche as- in Indo-European roots)

    From American Heritage Dictionary of the English Language, 5th Edition

  • From potassa (“potash") + -ium.

    From Wiktionary

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