Magnesium oxide, also known as magnesia or periclase, is a compound made up of magnesium and oxygen. It is commonly used as a dietary supplement, an antacid, and a component in refractory materials. Synonyms for magnesium oxide include magnesia, peroxide, magnesium(II) oxide, burnt magnesia, calcined magnesia, and magnesia alba. These synonyms may be used interchangeably with magnesium oxide depending on the context. Magnesia, in particular, is often used in medical settings to describe the compound when used as an antacid or laxative. Magnesium oxide is an important material in many fields and continues to be studied for its unique properties and potential applications.