||A mongrel, mutt, or mixed-breed dog, is a dog that is not the result of breeding within an existing breed or to modify or create a breed and belongs to no breed.
In the United States, the term "mixed-breed" is a favored synonym over "mongrel" among many who wish to avoid negative connotations associated with the latter term. The implication that such dogs must be a mix of defined breeds may stem from an inverted understanding of the origins of dog breeds. Pure breeds have been, for the most part, artificially created from random-bred populations by human selective breeding with the purpose of enhancing desired physical, behavioral, or temperamental characteristics. Dogs that are not purebred are not necessarily a mix of such defined breeds. Therefore, among experts and fans of such dogs, "Mongrel" is still the preferred term.