A physically mature person has a body that has naturally maximized its development with age.
A mentally mature person has developed a cognitive ability to think accurately, adequately, and independently.
A socially mature individual is a person who is willing to respond appropriately to his or her own needs and to respond benevolently to the needs and wants of others for whom he or she is responsible.
An emotionally mature person is one who accepts reality and continuously adjusts his or her perspective to changes in ways that enable him or her to do the best he or she can while enjoying every moment.