1911 Encyclopædia Britannica/Cassock
CASSOCK (Fr. casaque, a military cloak), a long-sleeved, close-fitting robe worn by the clergy and others engaged in ecclesiastical functions. The name was originally specially applied to the dress worn by soldiers and horsemen, and later to the long garment worn in civil life by both men and women. As an ecclesiastical term the word "cassock" came into use somewhat late (as a translation of the old names of subtanea, vestis talaris, toga talaris, or tunica talaris), being mentioned in canon 74 of 1604; and it is in this sense alone that it now survives. The origin of the word has been the subject of much speculation. It is derived through the French from the Italian casacca, which Florio (Q. Anna's New World of Words, 1611) translates as "a frock, a horseman's cote, a long cote; also a habitation or dwelling," and it is usually held that this in turn is derived from casa, a house (cf. the derivation of "chasuble," q.v.). This, however, though possible is uncertain. A Slav origin for the word has been suggested (Hatzfeld and Darmesteter, Dic. gén. de la langue française), and the Cossack horseman may have given to the West both the garment and the name. Or again, it may be derived from casequin (Ital. casecchino), rather than vice versa, and this in turn from an Arabic kazāyand (Pers. kashāyand), a padded jerkin; the word kasagân occurring in Mid. High Ger. for a riding-cloak, and gasygan in O. Fr. for a padded jerkin (Lagarde in Gött. gelehrte Anzeiger, April 15, 1887, p. 238).
The cassock, though part of the canonical costume of the clergy, is not a liturgical vestment. It was originally the out-of-doors and domestic dress of lay-people as well as clergy, and its survival among the latter when the secular fashions had changed is merely the outcome of ecclesiastical conservatism. In mild weather it was the outer garment; in cold weather it was worn under the tabard or chimere (q.v.); sometimes in the middle ages the name "chimere" was given to it as well as to the sleeveless upper robe. In winter the cassock was often lined with furs varying in costliness with the rank of the wearer, and its colour also varied in the middle ages with his ecclesiastical or academic status. In the Roman Catholic Church the subtanea (Fr. soutane, Ital. sottana) must be worn by the clergy whenever they appear, both in ordinary life (except in Protestant countries) and under their vestments in church. It varies in colour with the wearer's rank: white for the pope, red (or black edged with red) for cardinals, purple for bishops, black for the lesser ranks: members of religious orders, however, whatever their rank, wear the colour of their religious habit. In the Church of England the cassock, which with the gown is prescribed by the above-mentioned canon of 1604 as the canonical dress of the clergy, has been continuously, though not universally, worn by the clergy since the Reformation. It has long ceased, however, to be their every-day walking dress and is now usually only worn in church, at home, or more rarely by clergy within the precincts of their own parishes. The custom of wearing the cassock under the vestments is traceable in England to about the year 1400.
The old form of English cassock was a double-breasted robe fastened at the shoulder and probably girdled. The continental, single-breasted cassock, with a long row of small buttons from neck to hem, is said to have been first introduced into England by Bishop Harris of Llandaff (1729–1738). The shortened form of cassock which survives in the bishop's "apron" was formerly widely used also by the continental clergy. Its use was forbidden in Roman Catholic countries by Pope Pius IX., but it is still worn by Roman Catholic dignitaries as part of their out-of-door dress in certain Protestant countries.
See the Report of the sub-committee of Convocation on the Ornaments of the Church and its Ministers (London, 1908), and authorities there cited.