What do we mean by an Amenorrhea

An Amenorrhea is the absence of menstrual bleeding and may be primary or secondary.
Primary amenorrhea is the absence of menstrual bleeding and secondary sexual characteristics (for example, breast development and pubic hair) in a girl by age 14 years or the absence of menstrual bleeding with normal development of secondary sexual characteristics in a girl by age 16 years.
Secondary amenorrhea is the absence of menstrual bleeding in a woman who had been menstruating but later stops menstruating for 3 or more months in the absence of pregnancy, lactation (the ability to breastfeed), cycle suppression with systemic hormonal contraceptive (birth control) pills, or menopause.
For a woman to have regular menstrual cycles, her hypothalamus, pituitary gland (see Anatomy of the Endocrine System), ovaries, and uterus should all be functioning normally. The hypothalamus stimulates the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH cause the ovaries to produce the hormones estrogen and progesterone. Estrogen and progesterone are responsible for the cyclical changes in the endometrium (uterine lining), including menstruation. In addition, a woman’s genital tract should be free of any abnormalities to allow the passage of menstrual blood.