The monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause:
— 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.

synonyms: flow, menses, menstruation, menstruum, period.

Roget 138: periodicity, intermittence; beat; oscillation etc. 314; pulse, pulsation; rhythm; alternation, alternateness, alternativeness, alternity^†.    bout, round, revolution, rotation, turn, say.    anniversary, jubilee, centenary.    catamenia^†, courses, menses, menstrual flux.    [Regularity of return] rota, cycle, period, stated time, routine; days of the week; Sunday, Monday &c.; months of the year; January &c.; feast, fast &c.; Christmas, Easter, New Year's day &c.; Allhallows^†, Allhallowmas^†, All Saints' Day; All Souls', All Souls' Day; Ash Wednesday, bicentennial, birthday, bissextile^†, Candlemas^†, Dewali, groundhog day [U.S.], Halloween, Hallowmas^†, Lady day, leap year, Midsummer day, Muharram, woodchuck day [U.S.], St.    Swithin's day, natal day; yearbook; yuletide.    punctuality, regularity, steadiness.    ... show more

Dutch: menstruatie
Polish: menstruacja, okres, krwawienie miesiączkowe, period, miesiączka