noun
also ar·is ˈarə̇s also ˈer-
( plural arris or arrises also aris or arises )
Etymology: probably modification of Middle French areste arris, fishbone, beard of grain, from Late Latin arista fishbone, from Latin, beard of grain
: the sharp edge or salient angle formed by the meeting of two surfaces whether plane or curved — used especially of the edges in moldings and of the raised edges separating the flutings in a Doric column