menstruum

(noun) (archaic) a solvent.

(noun) the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause. Synonyms: menstruation, menses, catamenia, period, flow. Examples: "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."