Lighting that is low or moderate in contrast, such as on an overcast day. Light that has lost some intensity by being reflected or by passing through a translucent material. Diffusion softens light, eliminating both glare and harsh shadows, and thus can be of great value in photography, notably in portraiture. 
Lighting that is low or moderate in contrast; an overcast day is a good example.
3D cgi term. Lighting that is directional but soft, like illuminating something made of velvet or very dry skin