A stringed instrument contained in a large case of wood, having a double or treble row of distended strings, of brass and steel wires, supported by bridges. It is played upon similarly to the piano-forte, but instead of hammers covered with leather, the tone is produced by little upright pieces of wood, called jacks, furnished with pieces of crow-quill, which strike the wires. The piano-forte has now almost wholly superseded the harpsichord.