abat-jour
/əˌbatˈʒʊə/(also abajour, abatjour)
noun
An architectural device for deflecting the light from a wall or roof opening in a particular direction; specifically (a) a skylight set in an angled or slanting aperture or light well; (b) a screen on the outside of a window angled outward and upward so as to allow light into the room while at the same time obscuring the view below.
Origin
Mid 19th century; earliest use found in John Britton (1771–1857), antiquary and topographer. From French abat-jour, †abajour kind of skylight, light well, kind of shutter or screen on a window directing the daylight, kind of lampshade reflecting and directing the light from abat, 3rd singular present indicative of abatre to cast down + jour day, daylight.