(now rare) Occurring before the proper time; untimely, premature (especially of death). / Not fully formed or developed; not grown. / Childish in behavior; juvenile.

An immature member of a species.

Giving an appearance of immaturity. / Without maturity.

not having matured

The state or quality of being immature; immaturity

plural of immature

comparative form of immature: more immature

Youth; the condition of being immature or not fully grown

plural of immaturity

superlative form of immature: most immature