Dioneo is one of the three men of the brigata in The Decameron. His name is the Italian form of Dionysus, which in turn comes from the original Greek form Dionysos, after the god of wine, dance, and fertility. It’s derived from the elements Dios (of Zeus) and Nysa (a legendary mountain).
Dioneo has a special place in The Decameron, for he has the privilege of telling stories on any topic he feels like instead of keeping to the theme of the day. In exchange for this privilege, he must always go last (except for the first day). The theme of the seventh day, his turn as King, is tricks wives have played on their husbands. He also tells my favouritest Decameron story, the tenth story of the third day, where Rustico teaches Alibech how to put the Devil back into Hell. That story is the most famously raunchiest in the entire book.
Dianora may be an elaborated Italian form of Diana, and is a very rarely-used name. Dianora features in the fifth story of the tenth day, whose theme is magnanimity of character. She lives in the town of Udine, in Friuli Province, and is the wife of Messer Gilberto, a very wealthy and amiable fellow. Messer Ansaldo Gradense is in love with her, but she doesn’t love him in return.
To try to get him to back off, she makes a seemingly impossible request, for him to give her a garden as beautiful in January as in May. Towards this end, Messer Ansaldo employs a magician. When Dianora’s wish comes true, her husband demands she hold to her word and give Ansaldo what he wants just one time. He says he won’t consider it cheating if she gives her body but not her heart. Ansaldo is so moved when he hears this, he releases Dianora from her vow.
This story was later plagiarized by Chaucer as “The Franklin’s Tale,” one of a number of Decameron stories he co-opted.