Synonyms of 'infantile'
This kind of humour is infantile and boring.
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Babyish actions, feelings, or looks are like a baby's, or are immature.
I'm ashamed of the babyish nonsense I write.
I've never seen such selfish and childish behaviour.
Thesaurus for infantile from the Collins English Thesaurus
Infantile behaviour or illnesses are typical of very young children.