D defs.my
Entry 1 sense Webster, 1913

Arris

/ăr'-əs/ · Ar·ris · IPA /ˈæɹɪs/
01 n. The sharp edge or salient angle formed by two surfaces meeting each other, whether plane or curved; -- applied particularly to the edges in…
  1. 1.
    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.(Arch.)
Phrases & compounds
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.
Arris gutter — a gutter of a V form fixed to the eaves of a building.