immature
UK: ˌɪməˈtjʊə(r) | US: ˌɪməˈtʃʊr
adj. not fully developed or grown
adj. lacking emotional or intellectual maturity
adj. (of behavior) inappropriate for an adult
The word "immature" combines the Latin prefix "im-" (a variant of "in-" meaning "not") with the Latin root "maturus" (meaning "ripe" or "timely"). The term originally described physical ripeness (e.g., fruit) but evolved to describe human development—first biological, then psychological. The logic is straightforward: "not mature" implies incompleteness, whether in growth, judgment, or behavior.
The immature fruit was still green and hard.
His immature reaction to criticism embarrassed his colleagues.
Teenagers often display immature decision-making skills.
The project was abandoned due to immature technology.
She regretted her immature behavior during the argument.