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

(chemistry) KMnO₄, the most readily available commercial permanganate; it is used as an oxidizing agent both in industry and in the analytical laboratory.

(chemistry) a salt, KI, formally derived from potassium hydroxide and hydriodic acid, used as an analytical reagent, in organic synthesis, and in the preparation of photosensitive emulsions and as a radioprotector to protect the thyroid.

(organic chemistry) The potassium salt of benzoic acid.

(chemistry) The potassium salt of sorbic acid.

(chemistry) The potassium salt of nitrous acid, KNO₂.

(inorganic chemistry) KNO₃, a naturally occurring salt, notably used as an ingredient of gunpowder; also used a food preservative and as an ingredient in toothpaste for sensitive gums; historically used in the production of nitric acid (HNO₃).

(inorganic chemistry) A yellowish brown solid, KNH₂, obtained by heating potassium in ammonia gas. It is most commonly used as a base to create a carbanion of an enolate.

cream of tartar

(inorganic chemistry) An odorless, slightly basic substance which is soluble in water and often used to offset acidity.