An instance of menstruation, the part of each month during which a fertile woman menstruates.
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.
surrendering to the red army
How often have the words menstruation and surrendering to the red army occurred in a corpus of books? (source: Google Ngram Viewer )