From Longman Dictionary of Contemporary Englishinfantilein‧fan‧tile /ˈɪnfəntaɪl/ adjective 1 STUPID/NOT SENSIBLEinfantile behaviour seems silly in an adult because it is typical of a child SYN childish infantile jokes2 [only before noun] technicalMICHILD relating to or affecting babies and very young children infantile development
Examples from the Corpus
infantile• an infantile temper tantrum 