a square cap worn by ecclesiastics of the roman Catholic Church. A cardinals berretta is scarlet; that worn by other clerics is black, except that a bishops is lined with green. Also spelt beretta, biretta, etc.
Origin: It, fr. LL. Birrettum, berretum, a cap, dim. Of L. Birrus, birrum, a cloak to keep off rain, cf. Gr. Tawny, red: cf. Sp. Birreta, pg. Barrete, and E. Barret.