What does louver mean?
A louver is an angled slat used in a blind, window, door, or ventilation device. By overlapping such slats, a builder can admit light or air while reducing glare, hiding an interior, or controlling how strongly air flows into a room. The word is especially common in American technical, architectural, and industrial contexts, where a plural can refer either to a collection of individual slats or to a complete louvered assembly. Louvers are distinct from shutters, which are usually larger hinged panels, and from plain vents, which may consist of fixed openings rather than movable slats. Although a louver may serve mainly as a light-control feature, ventilation is one of its most recognizable practical uses. The term is also useful figuratively in descriptions of curved or patterned surfaces, such as car grilles and decorative panels, where repeated slats create depth and texture.
nounA narrow, typically horizontal slat fixed at an angle in a window, blind, door, or similar structure. The slats can admit light or air while limiting glare, visibility, or airflow.
- A horizontal slat set at an angle in a blind, window, door, or other structure.
- A device or opening composed of adjustable slats, used to regulate airflow, light, or visibility.
"She opened the louvered blinds to let in the cool morning air."
"The louvers were adjusted to direct air toward the ceiling."
"A row of metal louvers covers the ventilation opening on the side of the building."
The plural is standard for both a collection of individual slats and a louvered structure or ventilation assembly.
"The technician cleaned the louvers and adjusted their angle."
A louver does something counterintuitive with light: it lets some in while deliberately blocking the direct view.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of louver
The word comes through Middle English from an Anglo-French or Old French term associated with a sloping roof or projecting structure. Its modern English sense developed in two principal directions: the projecting roof feature associated with the spelling louvre, and the angled slats used in blinds and ventilation systems, commonly spelled louver in American English.
Related word forms
How louver is actually used
The singular commonly denotes one slat, while the plural often denotes a set of slats or an adjustable structure. Louver is especially common in American technical and architectural usage; British English more often spells the word louvre.
Easily confused with louver
Louver is the usual US spelling for an angled slat or a structure fitted with such slats, while louvre is the standard British spelling.