Other forms: retrievers
If your dog brings back anything you throw for her, she's a retriever. Many retrievers are bred to work alongside hunters, fetching game birds.
Even if your pup looks more like a mop than a Labrador retriever, you can still describe him as a retriever if he's intent on recovering every tennis ball you hurl across your yard. A retriever is a person or animal that retrieves things, or brings them back. So, strictly speaking, you're a retriever too, if you grab the runaway balls during your friends' tennis match! Retriever derives from the French verb trouver, "to find."