When a woman menstruates, a flow of blood comes from her womb. Women menstruate once a month unless they are pregnant or have reached the menopause. Lean hard-training women athletes may menstruate less frequently or not at all. + menstruation men·strua·tion Menstruation may cease when a woman is anywhere between forty-five and fifty years of age. when a woman menstruates, usually every month, blood flows from her body (past participle of menstruari, from menstruus , from mensis )
[ 'men(t)-strü-"wAt, 'men-" ] (intransitive verb.) 1800. Late Latin menstruatus, past participle of menstruari, from Latin menstrua menses, from neuter plural of menstruus monthly, from mensis.