Sir is a formal English honourific address for men, derived from Sire in the High Middle Ages. Traditionally, as governed by law and custom, Sir is used for men titled knights i.e. of orders of chivalry, and later also to baronets, and other offices. As the female equivalent for knighthood is damehood, the suo jure female equivalent term is typically Dame. The wife of a knight or baronet tends to be addressed Lady, although a few exceptions and interchanges of these uses exist.
