louver

A framed opening, as in a wall, door, or window, fitted with fixed or movable horizontal slats for admitting air or light and often for shedding rain.

One of the slats used in such an opening.

One of the narrow openings formed by such slats.

A slatted, ventilating opening, as on the hood of a motor vehicle.

A lantern-shaped cupola on the roof of a medieval building for admitting air and providing for the escape of smoke.

A form of lantern or turret rising from the roof of a hall or other apartment in medieval domestic edifices, at first open at the sides.

A chimney-flue.

In architecture, a long window-like opening closed with broad slats sloping downward and outward. See abat-vent.

The aperture in a dove-cote at which the bird enters; also, the dove-cote itself.