Una-corda. Meaning “one string,” this stop adjusts the position of the keyboard and action sideways, so that the hammer heads miss one of the trichord and bichord strings. More commonly employed on grand pianos, it is operated by the left pedal.

Under-damper. A type of upright piano action where the damper operates below the hammer head.

Upright grand pianoforte. A grand piano enclosed in a rectangular case and placed upright on a stand ; it was introduced by Robert Stodart in 1795.

Upright pianoforte. A piano constructed in a vertical case. The prototype of a modern piano in which the strings pass behind the keyboard to the bottom of the case, resting on the floor was created by Hawkins in 1800; Muller’s ‘Ditanaklasis’ (1800) also had vertical stringing.

V-bar. Ridge cast into the iron plate on upright pianos to fret the strings just before the pressure bar.

Velocity sensitive. The effect of attack on the key. If you play the key harder, the instrument plays louder, while an easier keystroke plays softer. Many keyboards do not have this critical feature. Nearly all digital pianos have this feature.

Vertical pianos. Instruments that measure about 5 feet wide (left to right) and about 2 feet deep (front to back). Their flat back is usually placed against a wall. Also known as upright pianos.

Viennese action. see Prellmechanik.

Vis a vis (Fr.). A term applied for a keyboard instrument with two keyboards, one at each end.

Voices. On digital pianos, voices represent instrument sounds.

Voicing (tone regulating). Process of shaping, hardening or softening hammer felt consistency to adjust tone.

Wippen. A rocking lever that transmits the motion of the key to the hammer.

Wrest pin. A 7mm-diameter steel pin around which the string is wound. By turning the wrest pin, the string’s tension can be altered and therefore its tuning. A small hole is drilled through the top of the pin to anchor the string and a fine thread is wound around its base so that it can be extracted from the wrest plank.

Wrest plank. A tough laminated, hardwood piece into which the wrest pins are driven. Its strength and accurate fitting beneath the iron frame is essential to the stability of the piano’s tuning.

Zuggetriebe [Zugmechanik] (Ger.). A term coined by W. Pfeiffer to describe a German action in which the motive force is transmitted to the hammer beak by a mobile escapement lever.