1. 年轻的;显得年轻的;富有青春活力的;朝气蓬勃的
Someone who is youthful behaves as if they are young or younger than they really are.
e.g. I'm a very youthful 50.
我50岁了，但仍富有青春活力。
e.g. ...youthful enthusiasm and high spirits...
青春的热情和高昂的情绪