1 youthful, teenage(d), adolescent, prepubescent, pubescent, juvenile, minor, junior, under age:
Would you believe that she has young children?
2 boyish, girlish; immature, callow, green, inexperienced, unfledged, uninitiated, unsophisticated, childlike, innocent, naïve:
This programme may contain material unsuitable for young ears.
3 childish, puerile, infantile, babyish, US sophomoric:
He's too young to invite to the party.
4 offspring, babies, issue, little ones, progeny, litter, brood; children:
The cat's young should stay with her for a few weeks.