Interestingly, the false name given to Vespucci and passed on to Vasari.  Conceals the real name of the subject in Leonardo’s painting.  Vespucci believed he heard the name Lisa del Giocondo.  Since the physical and historical evidence fails to support Vespucci’s claim.  It is evident Vespucci did not hear a name but one of Leonardo's famous word plays.  In Italian a wordplay is called a gioco di parole.  Vespucci misunderstood L' Isa del Giocondo for a name when it was a Gioco di Parole.   

            An Italian riddle revealing the name of the Leonardo's subject and painting title.  "L' Isa del Giocondo" is a direct translation of "The Isa of The Jocund."  A riddle only understandable if the true subject and original painting title is known to the listener.  

            The Isa, the first part of the riddle.  Reveals the subject the painting, Isabella.  Leonardo began Isabella’s portrait in 1500, Vespucci recorded in Florence in 1503.  Added to the original name of Leonardo's painting, The Jocund.  The countries where Leonardo lived still call the painting by the original title, in Italy the painting is La Gioconda and in France La Joconde.  Creates the riddle the Isa of the Jocund.

            Additionally, Lisa del Giocondo would not have been known by the name modern historians attribute to her.  During the renaissance, it was customary for ladies to keep their father's name rather than adopting their husband's surname.  Isabella was known as Isabella d'Este not Isabella Gonzaga, likewise Lucrezia Borgia rather than Lucrezia d'Este and Beatrice d'Este rather than Beatrice Sforza.  Accordingly Lisa was not know as Lisa del Giocondo but Lisa di Gheradini.  

            Illuminating Vasari's adaptation of the subject in his book.  Vasari does not refer to the subject as Lisa del Giocondo, instead she becomes the wife of Francesco del Giocondo, the Lady Lisa.  In Italian reads,             

                             Prefe Leonardo a fare per Francesco del Giocondo il ritratto di Mona Lisa sua moglie.

           This is why when Vasari attempts to attach the riddle to a person it becomes Byzantine.  Vasari never refers to the subject's name Lisa di Gheradini.  In a round about way Vasari refers to Leonardo's subject as the wife of Mr. Giocondo.  Attempting to tie Vasari's tale of Lisa del Giocondo to a historical person Lisa di Gheradini.  Vasari never calls the subject Lisa del Giocondo, because historically that name was never attributed to a person.  

            The colloquial term derived from Vasari's story, Mona Lisa is further misleading.  While poetic it is inaccurate.  The original title of the painting is "The Jocund.  A reflection of Leonardo's lifelong relationship with the subject in the painting.   Jocund, means pleasant, helpful, agreeable, cheerful, merry and lighthearted.  Describing Leonardo's muse, friend, patron and at times political protection, Isabella.