Birretta - A square cap with three ridges or peaks on its upper surface, worn by clerics of all grades from cardinals downwards. The use of such a cap is prescribed by the rubrics both at solemn Mass and in other ecclesiastical functions. Its origin is somewhere in the 15th Century. It may be said in general that the biretta is worn in processions and when seated, as also when the priest is performing any act of jurisdiction, e. g. reconciling a convert. The college cap and ecclesiastical biretta have probably developed from the same original, but along different lines.

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