Lune (geometry)

In plane geometry, a lune is the concave-convex area bounded by two circular arcs, while a convex-convex area is termed a lens. The word "lune" derives from luna, the Latin word for Moon.

Formally, a lune is the relative complement of one disk in another (where they intersect but neither is a subset of the other). Alternatively, if A and B are disks, then L = A − A ∩ B is a lune.