biretta, stiff square hat with three or four rounded ridges, worn by Roman Catholic, some Anglican, and some European Lutheran clergy for both liturgical and nonliturgical functions. A tassel or tuft is often attached. The color generally designates the wearer’s rank. A biretta with four ridges is also worn as academic, nonliturgical dress by those holding a doctoral degree from a pontifical university (i.e., an institution established or approved directly by the Holy See) or faculty. See also religious dress.
The biretta developed from the medieval cap known as a birettum, or pileus. By the 16th century it had evolved through several forms and had essentially attained its present form. It is often worn above a zucchetto (skullcap) to protect the biretta from wear.