Wikipedia
Cucoloris
In lighting for film, theatre and still photography, a cuculoris (occasionally also spelled cucoloris, kookaloris, cookaloris or cucalorus) is a device for casting shadows or silhouettes to produce patterned illumination. The word is sometimes shortened to cookie or coo-koo. The cookie is used to create a more natural look by breaking up the light from a man-made source. It can be used to simulate movement by passing shadows or light coming through a leafy canopy.