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.

plural of potassium

(obsolete, chemistry) potassium plumbate

(obsolete, inorganic chemistry) potassium carbonate

(biology) A small pore in a cell membrane that is selective to potassium ions and has several regulatory functions.

(chemistry) A potassium salt of chromic acid, K₂CrO₄; the yellow crystals are soluble in water, and it is used as an analytical reagent.

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

(obsolete, inorganic chemistry) potassium chromate

(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

(chemistry) A potassium salt of chromic acid, K₂Cr₂O₇; the orange crystals are soluble in water, and it is used as an oxidizing agent and in photography.