louvre

{ } n. [ OE. lover, OF. lover, lovier; or l'ouvert the opening, fr. overt, ouvert, p. p. of ovrir, ouvrir, to open, F. ouvrir. Cf. Overt. ] (Arch.) A small lantern. See Lantern, 2 (a). [ Written also lover, loover, lovery, and luffer. ]

2. Same as louver boards, below [ PJC ]

3. A set of slats resembling louver boards, arranged in a vertical row and attached at each slat end to a frame inserted in or part of a door or window; the slats may be made of wood, plastic, or metal, and the angle of inclination of the slats may be adjustable simultaneously, to allow more or less light or air into the enclosure. [ PJC ]

Louver boards or
Louver boarding, the sloping boards set to shed rainwater outward in openings which are to be left otherwise unfilled; as belfry windows, the openings of a louver, etc. --
Louver work, slatted work.