Duchessness

It would make little difference to most of us now whether the Duchess of Portland or her stand-in had posed—except that both might be lacking in any abstract quality of ‘Duchessnesss’.

Source: wiktionary

Take tippy-top care of your Duchessness. / Hugs, / Bess / […] / > With Love & Hugs, / > Rosie S. / > Demented Duchess

Source: wiktionary

If she had a brother she wouldn't be a duchess, she'd just be a <*insert less nobby title for unnecessary sprogs of nobles after the succession has been assured by the birth of an older or male heir*>. / […] pTerry has asserted her accepted duchessness (e.g. her dealings with the Gaiters in Hogfather, for one) so I think that's definite in any case.

Source: wiktionary

By the time Sam swung the camera around to face me, I was pouring tea like I had been born to it. I even had enough wits about me to say, with much duchessness, “Thank you, Palmer, that will be all. I will ring if I need you.” / “As you like, Your Grace. I shall go attend to the many and varied duties which Your Graces have bestowed upon me.”

Source: wiktionary