ˌRed Light ˈGreen Light noun [uncountable]
a game played by children in which one child stands a few metres away from the other players with his or her back to them. The other players try to get nearer to him or her, but they are only allowed to move forward when the child says ‘green light’ and must stop moving forward when he or she says ‘red light’ and turns round quickly to try and see anyone who is still moving. If the child sees someone moving, they have to go back to the beginning again. The winner is the first player to reach the child without being seen to move.

[TahlilGaran] Dictionary of Contemporary English ▲