ˌmenztrəˈwāshən, ˌmen(t)str-, ÷menzˈtrā-, ÷men(t)ˈstrā- noun
( -s )
Etymology: Late Latin menstruatus + English -ion
: a discharging of blood, secretions, and tissue debris associated with necrotic changes of the uterine mucosa that recurs in nonpregnant breeding-age females of various primates at intervals of 3 1/2 to 5 weeks (as in women typically at 4 week intervals and lasting 3 to 5 days) and that is usually held to represent a readjustment of the uterus to the nonpregnant state following proliferative changes accompanying the preceding ovulation ; also : an instance of the occurrence of this discharging : period