1. 孩子的;孩子般的
Childish means relating to or typical of a child.
e.g. ...childish enthusiasm.
孩子般的热情
2. (尤指成年人)幼稚的，孩子气的
If you describe someone, especially an adult, as childish, you disapprove of them because they behave in an immature way.
e.g. ...Penny's selfish and childish behaviour...
彭妮自私、幼稚的举动
e.g. Don't be so childish.
别这么不懂事。