From The Collaborative International Dictionary of English v.0.48 :
Menstruation \Men`stru*a"tion\, n. The discharge of the menses; also, the state or the period of menstruating. [1913 Webster]From WordNet (r) 3.0 (2006) :
menstruation n 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 [syn: menstruation, menses, menstruum, catamenia, period, flow]