lunette

(lo͞o-nĕtˈ)

1. Architecture
   a. A small, circular or crescent-shaped opening in a vaulted roof.
   b. A crescent-shaped or semicircular space, usually over a door or window, that may contain another window, a sculpture, or a mural.
2. A fortification that has two projecting faces and two parallel flanks.
3. A broad, low-lying, typically crescent-shaped mound of sandy or loamy matter that is formed by the wind, especially along the windward side of a lake basin.