Menorrhagia: Excessive uterine bleeding occurring at the expected intervals of the menstrual periods. The bleeding from the uterus starts on schedule but is heavier than usual and may last longer than usual. Menorrhagia may be a sign of an underlying disorder, such as hormone imbalance, endometriosis, uterine fibroids or, rarely, cancer of the uterus. Menorrhagia may cause significant anemia. See also: Menometrorrhagia; Metrorrhagia.