schoolboyish, boylike, macho, camp, machismo, effeminate, immature, effete, young, childlike, unmanly.
He was a slender, handsome youth with a delicate, boyish
Then she could hardly check the smile that rose to her lips; for there was stealing over his face a look that made it not merely boyish,
but little- boyish.
You have always come to me in the old boyish