Someone from either West Virginia, Minong Wisconsin, or the deep south. Are created by making children from other members of their family. This usually happens because they are so ugly the only other people that will have sex with them is members of their family. Easily noticable by lack of teeth, looking like they have been hit by a train, or bad english.
Billy is an inbred because he is his own grandfather.
Person conceived of breeding between two closely related couples, or someone with a very weak gene pool, but usually the former. Places famous for being rather inbred are some remote or scummy parts of the UK (where the chav population is high) and US redneck areas. This is a great shame for both countries as both have a typically wide gene pool due to different peoples settling over many hundreds of years. Also, royal circles are rather inbred too, for legitimacy reasons.
Eugh, look at the inbred...actually, second thoughts, don't.
A practice where closely related family members produce children. Because of this, the genes inherited may cause problems for the child where the child's genes may have suffered due to the lack of genetic diversity.
Royal families, neocons, and extremists are all the products of inbreeding.