Dame is an honorific title given to women who have been admitted to certain orders of chivalry. It is the female equivalent of Sir, the title used by knights. Baronetesses in their own right also use the title Dame. A woman appointed to the grades of Dame Commander or Dame Grand Cross of the Order of Saint John, the Order of the Holy Sepulchre, the Order of the Bath, the Order of Saint Michael and Saint George, the Royal Victorian Order, or the Order of the British Empire becomes a dame. A Central European order in which female members receive the rank of Dame is the Order of Saint George.
https://en.wikipedia.org/wiki/Dame