1. Instrument with its strings arranged vertically in an approximately triangular-shaped frame. Played by plucking the strings. The Wurlitzer Automatic Harp (made by Whitlock) was popular during the early 20th century. 2. Metal plate or frame which bears the tension of the strings in a piano. Correctly called a piano plate. 3. Large scale marimba struck with dense felt hammers. Used in pipe organs, particularly theatre and residence organs.