childish
- childlike
‘childish’
You say that someone is childish if you think they are behaving in a silly or immature way.
We were shocked by Josephine's selfish and childish behaviour.
Don't be so childish.
‘childlike’
You describe someone's voice, appearance, or behaviour as childlike when it seems like that of a child.
Her voice was fresh and childlike.
‘That’s amazing!' he cried with childlike enthusiasm.