ZUCCHETTO (biretum, submitrale, subbiretum, pileolus, calotta, Soli-Deo). - A hemispherical headdress, worn in white by the pope, red by cardinals (granted in 1464 by Paolo II, and in 1591 to regular cardinals by Gregorio XIV), purple by bishops (1867 by Pio IX), and black by abbots and by those who possess a privilege or indult (CIC 325; 625; 811, 2).
It was in use during the 14th century, since it may be seen beneath the tiara of Pope Clemente VI (d. 1353) on the tomb monument at La Chaise-Dieu. Its use spread during the 15th century (cf. Ordo Romanus XIV, 118: XV, 144: PL 78, 1272, 1351) and became general in the 16th and 17th centuries. In the 14th and 15th centuries it covered the entire occiput, gradually being reduced to its present small form. It may be worn during Holy Mass, outside the canon, but it is not permitted in Eucharistic processions or at the public exposition of the Blessed Sacrament. It is also worn beneath the mitre, and is therefore called submitale.