immature

adj

1.
characteristic of a lack of maturity
bairnish shirttail
Antonym:
mature
Derived from:
immatureness immaturity
2.
(used of living things especially persons) in an early period of life or development or growth
baby unwaxen youngling youngly youth youthly young
Derived from:
immatureness
3.
not fully developed or mature; not ripe
baby lime green unripe unripened
Derived from:
immatureness immaturity
4.
not yet mature
Antonym:
mature
Derived from:
immatureness immaturity
5.
(of birds) not yet having developed feathers
unfledged