Childish, puerile, sophomoric, infantile , juvenile. All mean immature to some degree.
young, immature
immature
The word "immature" is an adjective. It describes someone or something that is not fully developed, grown, or mature.
People were talking about how immature the boy was.
ish.---Actually, -ish is a suffix, not a prefix. A prefix is the front part of a word. For instance, take the word immature. That means childish, and the prefix is im- which means not. So an immature person is not mature, but childish.If you want another suffix for child that makes the meaning the same, you can add -like. So a person can be childlike.
sophmoric means immature so sophmoric humor is immature humor
Immature can mean childish or stubborn. The immature boy did not want to tie his shoes, and then fell.
immature
You are immature.
She ended the relationship because he was too immature.Your immature actions resulted in your ban.The thought was a rather immature one.
imago
Immature, silly, youthful, childlike, naive, infantile, babyish.