1. 青年时期;青少年时代
    Someone's youth is the period of their life during which they are a child, before they are a fully mature adult.

youth的解释

    e.g. In my youth my ambition had been to be an inventor.
           我年轻时的抱负是成为一个发明家。
    e.g. ...the comic books of my youth.
           我少年时代看的漫画书

2. 青春;朝气;年轻
    Youth is the quality or state of being young.

    e.g. Gregory was still enchanted with Shannon's youth and joy and beauty...
           格雷戈里仍为香农的朝气、快乐和美丽着迷。
    e.g. The team is now a good mixture of experience and youth.
           这个队如今既经验丰富又充满朝气。

3. （新闻用语，尤指惹麻烦的）青年，小伙子
    Journalists often refer to young men as youths, especially when they are reporting that the young men have caused trouble.

    e.g. ...gangs of youths who broke windows and looted shops...
           打碎玻璃橱窗抢劫商店的成群的年轻人
    e.g. A 17-year-old youth was remanded in custody yesterday.
           一名17岁的年轻人昨天被还押候审。

4. （统称）青年，年轻人
    The youth are young people considered as a group.

youth的反义词

    e.g. He represents the opinions of the youth of today...
           他代表着当今年轻人的看法。
    e.g. She's not a very good influence on the youth of this country.
           她对这个国家的青年一代没什么好影响。