What is Menopause?
Menopause is the point in a woman's life when menstruation stops permanently, signifying the end of her ability to have children. Known as the "change of life," menopause is the last stage of a gradual biological process in which the ovaries reduce their production of female sex hormones--a process which begins about 3 to 5 years before the final menstrual period. This transitional phase is called the climacteric, or perimenopause. Menopause is considered complete when a woman has been without periods for 1 year. On average, this occurs at about age 50. But like the beginning of menstruation in adolescence, timing varies from person to person.

National Institute of Health Menopause

North American Menopause Society