the period of time, usually from three to five days, during which menstruation occurs
3.
the matter discharged during menstruation
Word origin
C16: from Latin, pl of mensis month
menses in American English
(ˈmɛnˌsiz)
plural noun
the periodic flow of blood and sloughed-off tissue from the uterus, discharged through the genital tract: it normally occurs about every four weeks in a woman who is not pregnant, from menarche to menopause