menstruation

Etymology

menstruum + -ation, modelled after Late Latin menstruatio. The word is cognate with French menstruation, Spanish menstruación., displaced Old English monaþblod, mōnaþ + blōd.

noun

1. The periodic discharging of the menses, the flow of blood and cells from the lining of the uterus in unfertilized females of humans and other primates.
   It would seem that in Avebury, Stonehenge, and Malta the mystery cult of menstruation/mensuration reached its most consummate development. 1981, William Irwin Thompson, The Time Falling Bodies Take to Light: Mythology, Sexuality and the Origins of Culture, London: Rider/Hutchinson & Co., page 267
2. An instance of menstruation, the part of each month during which a fertile woman menstruates.