Lunette

noun
- Something that has the shape of a crescent or half-moon, such as:

1. An opening in a vault, especially for a window.
2. 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.
3. A low crescentic mound (as of sand) formed by the wind.

- The figure or shape of a crescent moon.