The English idiom, “green light,” refers to the idea of getting permission for a project or proposal. This is often used in the context of the phrase, “to get a green light,” from someone or some group. It is also used in the phrase, “to give a green light,” where the action is attributed to the person giving permission.
In addition to the above uses, this idiom can also come in the form of a single word, “greenlight,” which is in idiomatic verb that means give permission. For example, someone can talk about the boss of a company “greenlighting” a project. This form of the idiom corresponds to other common phrases in English language, for example, the single word “blue-sky” that means to brainstorm something.
Accounts differ as to the actual origin of the term, “get a green light.” This phrase relates directly to the idea of driving a vehicle, which makes it a phrase used more commonly in countries with more personal vehicles than mass transit. Over time, the idea of a green traffic light giving permission to a vehicle to move ahead got abstracted into many instances of the figurative “green light” giving people permission to do things.
The phrase, “get a green light,” is very often used in a business context. Someone at almost any level of a company might ask someone above them, or in other cases, a corporate board, to greenlight some allocation of funds. Staffers might ask each other, “did they greenlight,” a certain proposal or idea, especially those associated with the allocation of funds. In other situations, team leaders or others might explain to a group of people that, “we need the green-light to go ahead,” with something. This use of the phrase makes it clear that a project or proposal has been tabled or postponed because of a specific lack of permission or clearance or implementation.
The above phrase is a good example of a phrase that can be used in a question form, affirmative form or negative form. As shown in examples above, someone can ask about, “getting a green light,” as well as stating that someone did or did not get a green light for something. These are fairly straightforward, yet colloquial, ways of talking about permission.