lunette

Lunette is a term with several distinct meanings, all drawing on the French word for “little moon.” In English-language usage, it most often refers to shapes and forms that are crescent or semicircular in outline, and it appears in architecture, military fortifications, and geological contexts.

In architecture, a lunette denotes a crescent-shaped space or opening, such as a window or niche with a semicircular head. This form can be decorative or functional within walls, vaults, or apses, adding a curved, light-catching element to a facade or interior space. In military architecture, the lunette is a specific outwork: a detached or semi-detached defensive position with two faces that project from a curtain wall to cover a ditch and to provide flanking fire.

In geology and archaeology, a lunette is a crescent-shaped depositional feature formed by winds and water at the margin of a former lake or desert basin. Lunettes typically consist of silts or sands and preserve a record of past shorelines and environmental conditions. They are important for reconstructing paleoenvironments and human settlement patterns around former lakes.

The term also exists in French with broader meanings related to lenses or eyeglasses, reflecting the lunar imagery that underlies the name. In English technical writing, lunette retains specialized senses tied to its crescent shape, appearing in discussions of architecture, fortifications, and sedimentary landforms.

See also terms for crescent or lunate shapes and related architectural or geological outliers.