An amice was a loose fitting garment worn by Romans over their tunics; it was also worn by priests and pilgrims. It is a form of vestment used today by Roman Catholic priests during mass.
W. H. De Puy, A.M., D.D. The People's Cyclopedia of Universal Knowledge Vol. 1 (New York, NY: Phillips & Hunt, 1879) 87
Courtesy the private collection of Roy Winkelman