supplementary light
nounUK /ˌsʌplɪˈmentəri laɪt/
US /ˌsʌpləˈmentəri laɪt/
Extra light that you add to help plants grow or to make a place brighter.
The farmer hung supplementary light above the seedlings so they would grow strong in winter.
RELATED WORDS
OTHER MEANINGS
2. A second light source used in photography to soften shadows.
The photographer set up a supplementary light to brighten the model's face.
3. An added lamp used in a room when the main light is not enough.
She turned on a supplementary light while reading in the dim corner.
4. Artificial lighting used in a studio to support the key light.
A small supplementary light filled in the dark side of the scene.