Definition:
"Bulimia nervosa" is a noun that refers to a serious eating disorder. People with bulimia often experience strong cravings for food, which leads them to eat a lot in a short period (this is called binge eating). After this, they might feel guilty or worried about gaining weight, so they try to get rid of the food by not eating for a while (fasting) or by making themselves throw up (self-induced vomiting).
In summary, bulimia nervosa is a serious eating disorder characterized by binge eating followed by attempts to avoid weight gain through fasting or vomiting.