LUNETTE

noun Etymology: French, from Old French lunete small object shaped like the moon, from lune moon Date: circa 1639 something that has the shape of a crescent or half-moon: as, an opening in a vault especially for a window, the surface at the upper part of a wall that is partly surrounded by a vault which the wall intersects and that is often filled by windows or by mural painting, a low crescentic mound (as of sand) formed by the wind, the figure or shape of a crescent moon