louver
lou.ver or lou.vre \'lu:-v*r\ \-v*rd\ n [ME lover, fr. MF lovier] 1: a roof lantern or turret often with slatted apertures for escape of smok e or admission of light in a medieval building 2a: an opening provided with one or more slanted fixed or movable fins to a llow flow of air but to exclude rain or sun or to provide privacy 2b: a finned or vaned device for controlling a flow of air or the radiation of light 2c: a fin or shutter of a louver - lou.vered aj