immature

adj. acting in a way that is silly or childish, especially for your age.

adj. exhibiting psychological or social behavior inappropriate for one's chronological age; puerile.

“It was very immature of him to start shouting just because he lost the game.”

“The manager's immature response to constructive criticism created a toxic atmosphere within the department, as he often resorted to personal insults during meetings.”

adj. not yet fully developed or grown.

adj. not having reached a state of full development or reproductive maturity.

“The immature birds still have gray feathers and cannot fly long distances yet.”

“The biologist noted that the immature specimens lacked the distinctive markings found on adults of the same species.”

adj. happening before the right or expected time.

adj. occurring before the natural or proper time; premature.

“The poet wrote a sad poem about the immature death of a young soldier.”

“In the nineteenth-century novel, the protagonist laments the immature end of his political career following the scandal.”

Archaic

n. an animal or plant that is not yet an adult.

n. an individual organism that has not yet reached sexual maturity or its final adult form.

“The researchers counted twelve immatures among the group of seals on the beach.”

“Distinguishing between immatures and females of this particular butterfly species requires careful examination of the wing patterns under a microscope.”

Technical