a white, crystalline salt or deliquescent solid, KOH, used in the manufacture of soap, glass, etc.: it is a very strong alkali and absorbs carbon dioxide from the air
See potassium hydroxide in American Heritage Dictionary 4
noun
A caustic white solid, KOH, used as a bleach and in the manufacture of soaps, dyes, alkaline batteries, and many potassium compounds. Also called caustic potash, lye, potash.