What is the name of the skullcap worn by the Pope?

The zucchetto (Italian for "small gourd" or the vegetable zucchini) also called pileolus in Latin, is a small skullcap worn by clerics of the Roman Catholic Church and within Anglicanism and Lutheranism. It was first adopted for practical reasons--to keep the clergy's head warm in cold, damp churches. All ordained members of the Roman Catholic Church are entitled to wear the zucchetto.

According to ecclesiastical hierarchy, different color pileolus denote different status within the Catholic clergy. Thus, the Pope wears a white zucchetto, cardinals wear red ones, bishops wear purple and priests wear black zucchettos. This tradition dates back to the old testament, in which jewish priests were required to cover their heads in the presence of God as a sign of humility. All clerics who have episcopal character retain the skullcap for most of the mass celebration.