The phrase "greenish light" is correct and usable in written English.
It can be used to describe a light that has a green tint or hue.
Example: "The room was filled with a soft, greenish light that created a calming atmosphere."
Alternatives: "green-tinted light" or "light with a green hue."
An eerie greenish light illuminates the hallways.
She was dimly visible through the soundproofed glass window, bathed in greenish light.
The rain whispered on the leaded window beside them, and a greenish light suffused this front half of the room.
It is lit by a mysterious, greenish light, and is presided over by an enigmatic, black-clad proprietress.
Most of our conversation took place standing on the balcony that rings Akeley Hall, Olds's pale silhouette illuminated by the greenish light of the diorama beside us.
Speak into the transmitter and your voice makes jagged graphs in greenish light on a fluorescent screen at the end of the vacuum tube.
Above and behind the musicians, the Roosevelt Arch glowed greenish, lit from below by energy-saving L.E.D.s.
To evoke the churning currents of the river where the Rhinemaidens protect the magic gold, the planks, bathed in greenish lights, undulate slowly.
The translucent white tabletops, the glass-panelled walls, the greenish lighting, and, most of all, the food evoke some utopian future where the people have renounced not just meat but also soil, in favor of brightly colored, hydroponically grown produce.
We could see the dancers in the half-darkness behind a row of greenish lights set on the floor at the back of the stage; when they entered, it was as though they were making their way through foliage.
"There emerges close before us a small spot in a sharp-greenish light, which becomes ever larger and larger and finally forms a bright, shining sunlike figure.
