In some European languages, 31 December is not known as New Year's Eve but by a variant of the name of Pope Sylvester I,
because it is the anniversary of his death according to the Roman Catholic calendar of saints.
The last day of the year is known as Silvester in German, Réveillon de la Saint-Sylvestre in French,
Notte di San Silvestro in Italian, Silvesteravond in Dutch, Sylwester in Polish, Silvester in Slovakian, Silvestr in Czech and Szilveszter in Hungarian.
Other languages know it as «Old Year's Eve», of course as a translated term.
More about this day can be found HERE