menstruum in WordNet English dictionary

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
   menstruation  menses  menstruum  catamenia  period  flow 
   
2. (archaic) a solvent
   menstruum