<p><strong>Noun</strong></p><ul><li>any of a series of narrow openings framed at their longer edges with slanting, overlapping fins or slats, adjustable for admitting light and air while shutting out rain.</li><li>a fin or slat framing such an opening.</li><li>a ventilating turret or lantern, as on the roof of a medieval building.</li><li>any of a system of slits formed in the hood of an automobile, the door of a metal locker, etc., used especially for ventilation.</li><li>a door, window, or the like, having adjustable louvers.</li></ul><p><strong>Verb (used with object)</strong></p><ul><li>to make a louver in; add louvers to: to louver a door.</li></ul>