The term "juvenile" refers to an organism that is not yet fully developed or mature. In biology, it often describes young animals, such as juvenile fish or juvenile birds, that have not reached their adult form or reproductive capability. Juveniles typically exhibit different physical characteristics and behaviors compared to their adult counterparts. In a broader context, "immature" can describe behaviors or attitudes that are not fully developed or are considered childish. This can apply to individuals, such as teenagers or young adults, who may display impulsive or irresponsible actions as they navigate the transition to adulthood.