Under Age
( too young to do it legally ... )
You are under age when the law says you are too young to do that thing. Example: "What are those kids doing smoking cigarettes? They are under age." Another example: "Maybe kids can drink alcohol in France. But in America they are under age."
The law says that only people above a certain age can do certain things legally, like buy cigarettes, drink alcohol or drive on public roads. You are "under age" until you reach the age when you are allowed to do it. Example: "Sorry, we can't serve you alcohol if you're under age." Another example: "I'm not under age. I'm 21." Another example: "I'll who are "under age" are not allowed by law to do certain things because they are too young. Another example: "I grew up on a farm, so we often drove when we were under age."