From Longman Dictionary of Contemporary Englishchildishchild‧ish /ˈtʃaɪldɪʃ/ adjective1[usually before noun]CHILD relating to or typical of a child opp adulta high childish laughher childish excitement2STUPID/NOT SENSIBLEbehaving in a silly way that makes you seem much younger than you really are – used to show disapproval syn immature opp matureDon’t be so childish!I wish politicians would stop this childish name-calling. ► To describe someone who is as innocent, eager etc as a child, use childlike. —childishly adverb —childishness noun [uncountable]
Examples from the Corpus
childish• He said he wouldn't go out with us if Jerry was going too - he's so childish!• Yet the stakes involved were not childish.• I told Vivienne I thought it was stupid, just childish.• I know that sounds very childish and naive, but think about it.• He made her feel cheap, disloyal, childish and socially inferior.• I'd like you to explain your childish behaviour.• You know how childish he can be.• the childishjoys of cottoncandy and carousels• Lee looked out over his half-moon glasses almost like a childishmadman.• I suppose it was childish of me, but I vowed to break Sir Thomas's, if I could.• He said it with a childishwonder that touched her.