Saint Sylvester gives December 31 its traditional French name, Réveillon de la Saint-Sylvestre.
Saint Sylvester I was bishop of Rome from 314 until his death on December 31, 335. His feast day is observed on the date of his death, which is why December 31 is called Saint-Sylvestre in French and several other European traditions.
Réveillon refers to a late-night festive meal or celebration. In France, the New Year's Eve gathering may include an elaborate dinner, champagne, music, and a midnight greeting. The name therefore combines the celebratory meal with the saint's calendar day.
Saint Sylvester is sometimes confused with Pope Sylvester II, who lived nearly seven centuries later and was associated with the year 1000. The New Year's Eve name refers to Sylvester I, not to the later pope or to a separate festival founder.