Synonyms and related words :
arrested, asinine, babish, babyish, backward, beardless, boyish, boylike, calflike, childlike, coltish, decrepit, doddering, doddery, doited, doting, fatuous, foolish, girlish, girllike, immature, inexperienced, infantile, infantine, juvenile, kiddish, maiden, maidenly, moronic, naive, puerile, puplike, puppyish, puppylike, retarded, senile, silly, simple, slow, sophomoric, underdeveloped, undeveloped, unsophisticated, wanting