From Longman Dictionary of Contemporary Englishchildishchild‧ish /ˈtʃaɪldɪʃ/ adjective 1 [usually before noun]CHILD relating to or typical of a child OPP adult a high childish laugh her childish excitement2 STUPID/NOT SENSIBLEbehaving in a silly way that makes you seem much younger than you really are – used to show disapproval SYN immature OPP mature Don’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 Corpuschildish• 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 childish joys of cotton candy and carousels• Lee looked out over his half-moon glasses almost like a childish madman.• I suppose it was childish of me, but I vowed to break Sir Thomas's, if I could.• He said it with a childish wonder that touched her.