Answer:
Juvenile as a noun means a young person, bird, or other animal; describes a person below the age at which ordinary criminal prosecution is possible; adolescent; youth; or teenager. Example sentence:
The juvenile could not be put into the cage with the adult chimps until it was strong enough to fend for itself.
Juvenile as an adjective is of, for, or relating to young people, birds, or other animals; childish; youthful; young; or adolescent. Example sentence:
My brother went to a juvenile facility when he was eight because my dad made him take the blame for shooting his uncle.
I wish they would let me use juvenile test subjects for my Cortexiphan experiments...