[ju.ve.nile] adj [F or L; F juvenile, fr. L juvenilis, fr. juvenis young person--more at young] (1625) 1 a: physiologically immature or undeveloped: young b: derived from sources within the earth and coming to the surface for the first time--used esp. of water and gas
2: of, relating to, characteristic of, or suitable for children or young people "~ books"
3: reflecting psychological or intellectual immaturity: childish
[2]juvenile n (1733) 1 a: a young person: youth b: a book for children or young people
2: a young individual resembling an adult of its kind except in size and reproductive activity: as a: a fledged bird not yet in adult plumage b: a 2-year-old racehorse
3: an actor or actress who plays youthful parts