Boccaccio uses the naming pattern of The Hexameron, St. Ambrose's series of six sermons on the Creation to create a portmanteau of the Greek δέκα ("ten") and ἡμέρα ("day"). So we get Decameron, ten days of stories. Why does he do this? Maybe he was trying to borrow some gravitas from the ecclesiastical work or perhaps—more probably—he's using this pattern of naming to parody this earlier, moralistic work.
He also gives us a "surname" for his work: "Prencipe Galeotto" or "Prince Galehaut." This "a.k.a" has caused debate among scholars. It's a clear literary shout-out to the character of the same name from French Arthurian romance tradition: Galehaut was the enemy of King Arthur who helped to bring Guinevere and Lancelot together. He was crushing on Lancelot himself, but gallantly stood aside and allowed the two lovers to meet and kiss for the first time. But even closer to home, the story of Galehaut is what brings Dante's eternally damned lovers Paolo and Francesca together (Inferno, V.137). They're reading the story of Lancelot and Guinevere and are overcome by passion. So what does this mean about the character or purpose of this book? Maybe it depends on whether you think the story of Lancelot hooking up with Guinevere was the proper consummation of a great love or a betrayal of the worst kind that caused the downfall of the legendary king. Maybe Boccaccio's warning us about what can happen when sexual attraction gets out of control, i.e. the damnation of Paolo and Francesca. We report; you decide.