n.  成人，成年人

n.  成年动物

a.  发育成熟的，成年的

a.  成人的；老成的，成熟的

• adulthood

  n.  成年 ≠ childhood

• adult children  成年后的孩子

• the adult population  成年人口 

• Whether you can successfully change your personality as an adult is the subject of a longstanding psychological debate.

  作为一个成年人

• “These patterns suggest that some types of mental flexibility decrease relatively early in adulthood, but that the amount of knowledge one has, and the effectiveness of integrating it with one's abilities, may increase throughout all of adulthood if there are no diseases,” Salthouse said in a news release. 成年早期，成年后

• dealing with problems in an adult way

  以成人的方式处理问题

BrE /ˈædʌlt/

NAmE /əˈdʌlt/