The area starting with the entire underside of the scrotum and extending to the anus. The main area of the baunch is the backside of the testicals with the secondary area of the baunch being that of the area between the testicals and the anus. Women are physiologically incapable of having a baunch.
Another term that is used for a womans vagina with a negative conotation. Could be a very smelly vagina, diseased vagina, fat vagina, or a sluts vagina.