underage

1. ADJ A person who is underage is legally too young to do something, for example to drink alcohol, have sex, or vote. (人)未到法定年龄的

Underage youths can obtain alcohol from their older friends. 未到法定年龄的孩子可以从他们年长的朋友那里得到酒。

2. ADJ Underage activities such as drinking or smoking are carried out by people who are legally too young to do them. (行为)未到法定年龄的[ADJ n]

...his efforts to stop underage drinking and drug abuse. ...他阻止未到法定年龄的人喝酒和吸毒的努力。