Juvenile; an organism that has not quite reached adulthood.
Stage in which an organism has developed many but not all adult characteristics and is not sexually mature. ... (09 Oct 1997) ... 
A developmental life stage when fish exhibit most but not all traits of an adult fish.
A bird that has not yet acquired definitive adult plumage but no longer has juvenal plumage.
a juvenile animal that is nearing sexual maturity.
a young bird that is sexually mature and capable of breeding but that does not yet exhibit characteristic plumage or marking of an adult of the species. For bird banding, a bird known to have hatched in the year preceding the year of banding.
Almost adult; the last instar before maturity.
A bird that has not yet reached maturity; immature.
Bird intermediate in age and plumage between immature and adult.