Biretta enters English from Italian biretta (also berretta), descending from the same Late Latin birrettum ("cap") that gives us the beret. The two words are thus doublets — two modern English words derived from the same ancestral form through different linguistic pathways. Beret traveled through Gascon French; biretta came through Italian. The divergence is not just linguistic but physical: the beret remained soft and round, while the biretta stiffened into a structured, square-topped cap with three or four pronounced ridges.
The biretta's form became standardized in Catholic ecclesiastical dress during the medieval period. Its rigid structure, typically made of stiffened silk or wool with a squared top, distinguishes it immediately from other headgear. The color system is codified: black birettas for priests and deacons, purple for bishops, red for cardinals, and white for Premonstratensian canons and some other orders. The red cardinal's biretta carries particular ceremonial significance — at the papal consistory where new cardinals are
The biretta's ridges (typically three, sometimes four) have generated various symbolic interpretations. Some theologians associate the three ridges with the Holy Trinity. Others see them as representing the three theological virtues (faith, hope, charity) or the three evangelical counsels (poverty, chastity, obedience). More prosaically, the ridges likely developed as structural reinforcement for the square shape.
The academic mortarboard — the square cap worn at graduation ceremonies — may share ancestry with the biretta, as medieval universities were ecclesiastical institutions and their dress codes overlapped with clerical vestments. The tasseled mortarboard evolved from the pileus quadratus ("four-cornered cap") worn by scholars and clergy alike in the medieval university system. The relationship is debated but plausible.
The biretta's use has declined since the Second Vatican Council (1962–1965), which relaxed many dress code requirements for Catholic clergy. However, it remains prescribed for certain liturgical occasions and has experienced a modest revival among traditionally-minded clergy. Like many elements of ecclesiastical vestment, the biretta functions as a visible marker of institutional identity, rank, and historical continuity — a textile language that communicates authority and belonging.