A Greek Orthodox Clergyman wearing an outer cassock]] The ''' cassock''', an item of clerical clothing, is a long, close-fitting, ankle-length robe worn by [[ clergy| clerics]] of the Orthodox Church, as well as many Western Christian denominations. The cassock derives historically from the tunic that was formerly worn underneath the toga in classical antiquity.
The word "cassock" probably comes from the Middle French ''casaque'' (cloak). In older days, it was known in Latin as ''vestis talaris''. Although the cassock was formerly the universal everyday clothing of the clergy, many, particularly in the west, have abandoned it in favor of a clerical suit of more modern design. In current usage, wearing the cassock may be a mark of a traditional cleric, though in the Orthodox Church, even those who generally do not wear cassocks continue to wear them during the services.