Childish synonyms such as foolish, adolescent, babyish, and fatuous. Childish is an adjective, and its antonyms are mature and sophisticated. Additionally, here are 26 synonyms, related words, and verbs for childish.
adolescent, boyish, bread-and-butter, child's, childlike, children's, girlish, teenage, teenaged, young, young-looking, and youthful.
babyish, fatuous, foolish, immature, inane, infantile, irresponsible, jejune, juvenile, naive, puerile, silly, and stupid.