noun The water-soluble part of wood ash, used for making soap and glass and as a fertilizer (chemically speaking, an impure form of potassium carbonate (K2CO3) mixed with other potassium salts).
noun Potassium. Chiefly used in the names of compounds of the form "... of potash".
permanganate of potash
noun A class of potassium minerals, of similar applicability to potassium carbonate, such as being a fertilizer. (ie. potassium chloride, potassium hydroxide)