The cassock ( or soutane) is the general term for the long, ankle length clerical gown worn by the priests of primarily the Catholic, Anglican, and Eastern Orthodox churches, a more elaborate version of the habit worn by the monastics
The word derives fropm the French casaque, meaning long coat , which in turn may well have come from the Persian kashagand, padded garment and the Turkish “quzzak”, referencing the buttoned coats of nomads and the source of the word Cossack.
Cassocks are many and varied, to those in the know, the colours, decorations and he particular structure of each type of cassock denotes the rank, position, era and religious attachment of the priest for whom it’s been made.