Gynecomastia: Excessive development of the male breasts. Temporary enlargement of the breasts is not unusual or abnormal in boys during adolescence or during recovery from malnutrition. Gynecomastia may be abnormal as, for example, in Klinefelter's syndrome.
Quick GuideThe Surprising Health Benefits of Sex
Subscribe to MedicineNet's General Health Newsletter
Last Editorial Review: 5/13/2016