Retriever isn't a single breed but a type of gun dog, developed to find shot birds and carry them back gently. On adoption listings it usually means a Labrador or Golden Retriever mix, or a dog with that look and unknown ancestry. Chesapeake Bay, Flat-Coated, Curly-Coated and Nova Scotia Duck Tolling Retrievers belong to the same family.
Most retriever-type dogs are medium to large, sturdy and food-motivated, with a water-resistant coat that sheds a good deal. Many are sociable, eager to work with people and happiest with something in their mouths. In Knoxville's humid climate with rain all year, that coat dries slowly after a swim, so expect some wet-dog smell. Because ancestry varies, meeting the dog tells you more than the label.