In regulation. Regulation is a process in which a technician makes a dozen or so critical adjustment to each of the 88 key mechanisms. The goal is to bring each key mechanism to factory specification and to have all the key mechanisms consistent with each other. When this process has been completed satisfactorily the piano is said to be in regulation.

In tune. A piano is considered to be in tune when its concert A note delivers a tone that is at 440 Hz or cycles per second, and the tone of the rest of the scale of the piano is consistent with itself.

Iron Frame. A cast metal component of the piano structure that is responsible for withstanding the strings tension.

Jack. A boot-shaped wooden lever that connects the lower parts of the action through to the hammer and forms an essential part of the escapement mechanism. In earlier actions it is called a hopper.

Janissary stop [Turkish music]. A pedal that operated a drumstick, which struck the underside of the soundboard, tuned bells and a cymbal to add ‘Turkish’ effects fashionable in late 18th- and early 19th-century Vienna.

Kapsel. A metal or wooden fork attached to the rear of the key in which the hammer pivots. (in Viennese or Prellmechanik actions).

Key. A balanced lever which when depressed operates the action.

keyboard. As it relates to acoustic pianos, the keyboard is the user interface of the instrument, the keys themselves, as a subassembly. As it relates to digital products, it may describe a category of small portable keyed instruments that sit on a table-top or on a folding stand. These typically do not have the regulation number is keys and the regulation size keys. Some folks mistakenly lump all electronic keyed products, including digital pianos, under this confusing title.

Keybottom. A solid wooden base on which the keyframe either sits or is attached.

Key chasing. A cloth lined mortise that works on the balance pin, found protruding on the top of all keys at their center.

Keyframe. A wooden framework on which the keys operate, consisting of the back-touch rail, the balance rail, and the front-touch rail.

Key top. Covers the surface of the natural keys. Traditionally made from ivory, it is now made from celluloid or plastic.

Knee lever. A lever attached to the underside of the key-bottom. Operated by the player’s knee, it most commonly lifted the dampers.

Legato. Indicates that musical notes are played or sung smoothly and connected.

Limited warranty. A warranty covering the original owner only. Other restrictions may apply.

Liner. A wooden rail glued round the inside of the piano case or rim to which the soundboard is glued.

Loud pedal. See SUSTAINING PEDAL.

Lost-motion. Any travel in the key that does not pass through the action.

Lyraflugel (Ger.). LYRE PIANO.

Lyre. The wooden frame, often decorated, which supports the pedals of a grand piano.

Lyre piano. A variant of the pyramid piano, current from c1830; the case was in the form of a lyre.