unjuvenile

Example:She had always been a mature individual, able to handle complex work situations.

Definition:Developed to a full grown state; fully developed in body, mind, or wisdom.

Example:The adult film actor always behaves in a mature and professional way on screen.

Definition:Coach or preside over events to determine a winner among a group of contestants; make or place a formal demand or claim; be suggestive sexually; behaving or showing oneself to be appropriate for an adult; (sport, not in soccer) compete in a match; (geology) a stage in which no new material is being added; mature, fully developed in body, mind and emotion.

Example:Despite her young age, she radiated a sophisticated air that was quite impressive.

Definition:Advanced in education or training or having acquired knowledge or skill through instruction or experience.