green light(redirected from a green light)
1. verb To permit someone or something to proceed. Likened to the green light of a traffic signal. Do you think the production company will green light our film?
2. noun Permission to proceed with some action or task. We're just waiting to get the green light from our managers before we release the latest software update.
green lightpermission to go ahead with a project.
The green light referred to is the traffic signal indicating that traffic is free to move forward. Red and green lights were in use from the late 19th century in railway signals, but this figurative use of green light appears to date from the mid 20th century.
1997 New Scientist Zemin even got the green light to buy nuclear power plants.