- an open turret or lantern on the roof of a medieval building
- a window or opening furnished with a series of overlapping, horizontal slats arranged so as to admit light and air but shed rain water outward
- any of these slats
- any similar arrangement of slats or fins, often adjustable, used to control ventilation, light intensity, etc.
- a ventilating slit
ME luver < MFr lover < MDu love, gallery (in a theater), akin to OHG louba: see lodge