-arris-

n. [ OF. areste, F. arête, fr. L. arista the top or beard of an ear of grain, the bone of a fish. ] (Arch.) The sharp edge or salient angle formed by two surfaces meeting each other, whether plane or curved; -- applied particularly to the edges in moldings, and to the raised edges which separate the flutings in a Doric column. P. Cyc. [ 1913 Webster ]

Arris fillet, a triangular piece of wood used to raise the slates of a roof against a chimney or wall, to throw off the rain. Gwilt. --
Arris gutter, a gutter of a V form fixed to the eaves of a building. Gwilt. [ 1913 Webster ]