The book's primary title exemplifies Boccaccio's fondness for Greek philology: Decameron combines two Greek words, δέκα, déka ("ten") and ἡμέρα, hēméra ("day"), to form a term that means "ten-day [event]". Ten days is the period in which the characters of the frame story tell their tales.
Boccaccio's subtitle, Prencipe Galeotto (Prince Galehaut), refers to Galehaut, a fictional king portrayed in the Lancelot-Grail who was sometimes called by the title haut prince ("high prince"). Galehaut was a close friend of Lancelot and an enemy of King Arthur. When Galehaut learned that Lancelot loved Arthur's wife, Guinevere, he set aside his own ardor for Lancelot in order to arrange a meeting between his friend and Guinevere. At this meeting the Queen first kisses Lancelot, and so begins their love affair.
In Canto V of Inferno, Dante compares these fictional lovers with the real-life paramours Francesca da Rimini and Paolo Malatesta, whose relationship he fictionalises. In Inferno, Francesca and Paolo read of Lancelot and Guinevere, and the story impassions them to lovemaking.
Dante's description of Galehaut's munificence and savoir-faire amidst this intrigue impressed Boccaccio. By invoking the name Prencipe Galeotto in the alternative title to Decameron, Boccaccio alludes to a sentiment he expresses in the text: his compassion for women deprived of free speech and social liberty, confined to their homes and, at times, lovesick. He contrasts this life with that of the menfolk, who enjoy respite in sport, such as hunting, fishing, riding, and falconry.