Mature, grown-up, old enough (with the implication that one can look after oneself and make one's own decisions).
Pertaining to any of several supposedly critical years of a person's life.
Critical or crucial; decisive.
Climactic.
Relating to a period of physiological change during middle age; especially, menopausal.
The period of life that leads up to and follows the end of menstruation in women; the menopause.
A critical stage or decisive point; a turning point.
A period in human life in which some great change is supposed to take place, calculated in different ways by different authorities (often identified as every seventh or ninth year).