Ammonium alum is a type of double salt that is widely used for various purposes. It is also commonly known as ammonium aluminum sulfate and ammonium sulfate alum. However, there are several other synonyms for this compound, such as aluminum ammonium sulfate, aluminum ammonium bisulfate, aluminum ammonium disulfate, and aluminum sulfate ammonium. These synonyms are reflective of the compound's chemical composition and its various uses in different industries such as cosmetics, food, and water purification. While these terms may seem interchangeable, it's essential to recognize the subtle differences between them, as they can affect the compound's performance and application.