From Longman Dictionary of Contemporary Englishgreen lightˌgreen ˈlight noun [countable] 1 TTCa traffic light that shows cars they can go forward2 → give somebody/something the green light
Examples from the Corpus
green light• The president gave him a green light, and in the next three years he re-created his role at the company completely.• I get a few qualms just before the green light comes on.• But after waiting years for the building permits, Rohr got the green light to build just as the market turned down.• Doctors gave him the green light yesterday to start against New Orleans on Sunday night.• So only one option in those situations-the green light.From Longman Business Dictionarygreen-lightˈgreen-light verb [transitive] to approve a project, plan etc so that it can beginColumbia green-lighted the film with a budget of $28 million. 