Source : Webster's Revised Unabridged Dictionary (1913)

Menstruation \Men`stru*a"tion\, n.
   The discharge of the menses; also, the state or the period of
   menstruating.

Source : WordNet®

menstruation
     n : 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: {menses},
          {menstruum}, {catamenia}, {period}, {flow}]