infantile

1. ADJ Infantile behaviour or illnesses are typical of babies or very young children. 婴儿的; 幼儿的[正式] [ADJ n]

...infantile aggression. ...婴儿期的攻击行为。

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

This kind of humour is infantile and boring. 这种幽默既幼稚又无聊。