A polite way of addressing a duchess, who might more formally be calied ‘your Grace’. Used by some men, especially Londoners, to their wives, since ‘my old Dutch’ has long been a Cockney way of referring to one’s wife....

A duke is a noble person, historically of highest rank below the King or Queen, and usually controls a duchy or a Dukedom. The title comes from the Latin Dux Bellorum, which had the sense of "military commander" and was employed both by the Germanic...