infantile

1. ADJ Infantile behaviour or illnesses are typical of babies or very young children. 嬰兒的; 幼兒的[正式] [ADJ n]

...infantile aggression. ...嬰兒期的攻擊行為。

2. ADJ If you accuse someone or something of being infantile, you think that they are foolish and childish. 幼稚的[表不滿]

This kind of humour is infantile and boring. 這種幽默既幼稚又無聊。