a stage of the female reproductive cycle. An ovum (egg) matures and is released every month. Hormones are released to prepare the uterus for possible implantation. If pregnancy does not occur, the uterine lining (blood and tissue) is shed and expelled (the menstrual period).
MENSTRUATION
Meaning of MENSTRUATION in English
AIDS English Glossary. Английский словарь СПИДа. 2012