Man-made illumination not limited to the indoor variety: fluorescent bulbs, jack-o'-lantern, or car headlights. It usually has lower color temperature than natural light, thus more reddish qualities. (See color temperature, natural light).
Light source other than the sun. Includes grow lights, which are generally fluorescent and provide the full range of light (i.e., blue light to red light) necessary for African Violets and other plants to grow.