1 [usually before noun]
relating to or typical of a child [≠ adult]:
a high childish laugh
her childish excitement
behaving in a silly way that makes you seem much younger than you really are - used to show disapproval [= immature; ≠ mature]: ! This word is generally used to suggest someone's behaviour is silly or immature. To talk about positive qualities connected with children, use childlike.
Don't be so childish!
I wish politicians would stop this childish name-calling.
—childishness noun [uncountable]