Menstruation

n. cyclical discharge of blood from the nonpregnant uterus of a woman, woman's monthly discharge of blood, menstrual cycle, menstrual period (Physiology)

Menstruation is a phase of the menstrual cycle in which the uterine lining (endometrium) is shed. Menstrual cycles occur exclusively in humans and other apes. The females of other species of placental mammal experience an estrus, in which the endometrium is reabsorbed by the animal at the end of its reproductive cycle.
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Menstruation /men·stru·a·tion/ the cyclic, physiologic discharge through the vagina of blood and muscosal tissues from the nonpregnant uterus; it is [more]Menstruation - Community and Resources

Noun
1. the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause; "the women were sickly and subject to excessive menstruation"; "a woman does not take the gout unless her menses be stopped"--Hippocrates; "the semen begins to appear in males and to be emitted at the same time of life that the catamenia begin to flow in females"--Aristotle
(synonym) menses, menstruum, catamenia, period, flow
(hypernym) discharge, emission, expelling
(hyponym) menorrhagia, hypermenorrhea
(derivation) menstruate, flow

n. menstruation, catamenia, menorrhea, cyclical discharge of blood from the nonpregnant uterus of a woman, menstrual cycle, menstrual period (Physiology)