arris

noun

ar·​ris ˈa-rəs 

ˈer-əs

plural arris or arrises

: the sharp edge or salient angle formed by the meeting of two surfaces especially in moldings

Word History

Etymology

Middle English (in compound araswise), borrowed from Middle French areste "awn of an ear of grain, fish bone, edge formed by the meeting of two planes," going back to Old French, going back to Latin arista "awn of an ear of grain, ear of grain" (Late Latin also, "fish bone"), perhaps of substratal origin

Note: The common image behind the various meanings is that of an axis from which parallel lines radiate in opposing directions, like the awn of a grain spike, or a fish skeleton viewed laterally. The image was extended in French to the arris of a groin vault, where the courses of masonry meet the angle of the vault diagonally in a pattern suggesting the skeleton of a fish. See also arête.

First Known Use

15th century, in the meaning defined above