Arris

In architecture, an arris is the sharp edge formed by the intersection of two surfaces, such as the corner of a masonry unit;

the edge of a timber in timber framing; the junction between two planes of plaster or any intersection of divergent architectural details. The term also refers to the raised edges which separate the flutings in a Doric column.

The origin of the term arris is from the Latin arista, meaning the beard or the ear of grain or the bone of a fish. See also arête.