ClipArt ETC
"A vertical series of sloping roofs or broad slats, inclined outward and downward, forming the filling of a belfry-light, and designed to admit ventilation to the timber frame while protecting the interior from rain and wind, and to direct downward the sound of the bells."-Wright, 1902

Abat-vent

"A vertical series of sloping roofs or broad slats, inclined outward and downward, forming the filling…