infantilism infantile • infantility · · · Info · Definitions · Characters · · infantilism · · Text Latin · · Script 11 · · Length Definitions · · · (noun) an abnormal condition in which an older child or adult retains infantile characteristics. · · Noun Definition 1 (noun) infantile behavior in mature persons. · · Noun Definition 2 Characters · · a latin small letter a U+0061 f latin small letter f U+0066 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E s latin small letter s U+0073 t latin small letter t U+0074