zucchetto, small skullcap worn by Roman Catholic clergy. The zucchetto is often worn on its own, as well as under the mitre. It can also be used under the biretta or papal tiara to help protect them from wear. Bishops, including cardinals, archbishops, and the pope, may wear a zucchetto during the mass but must remove it during the liturgy of the Eucharist; other ecclesiastics are not permitted to use the cap during the mass unless they have special permission.
The zucchetto was developed from the pileus—a close-fitting, brimless hat commonly worn by the Romans—and has probably been worn by ecclesiastics since the 13th century. It is likely that the cap was originally used to cover the tonsured (shaved) heads of clergy in cold churches. Each zucchetto consists of eight triangular panels of silk or polyester sewn together, often with a small stem on top, and the color of the cap depends on the wearer’s ecclesiastical rank.