Menarche

Menarche ( /mɨˈnɑrkiː/ mə-NAR-kee; Greek: μήν mēn "moon" + ἀρχή arkhē "beginning") is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives it is often considered the central event of female puberty, as it signals the possibility of fertility.