The harp guitar (or "harp-guitar") is a guitar-based stringed instrument with a history of well over two centuries. While there are several unrelated historical stringed instruments that have been referred to as "harp-guitar" over the centuries, its most common definition is a "guitar, in any of its accepted forms, with any number of additional unstopped strings that can accommodate individual plucking." The word "harp" is used in reference to its harp-like unstopped open strings.