Cope. A large, loose outer garment; a cloak; a mantle. A large mantle of silk or brocade worn by catholic priests in processions. As distinguished from the chasuble, the cope is a processional or choral vestment, while the chasuble is sacrificial or eucharistic. In the University of Cambridge, England, the ermine robe worn by a doctor in the senate-house on congregation day is called a cope.