Synonyms and related words :
asinine, babish, babyish, beardless, boyish, boylike, calflike, childish, childlike, coltish, foolish, girlish, girllike, immature, inconsequential, infantile, infantine, insignificant, irresponsible, juvenile, kiddish, maiden, maidenly, puplike, puppyish, puppylike, ridiculous, shallow, silly, sophomoric, trivial