These pages comprise a dictionary of terms relating to the pipe organ. Please keep definitions to a few sentences, and do not include pictures or sound clips. When more space is needed for a term, a new page can be created for it.


Façade [noun] that portion of an organ which is visible from the room into which it speaks. A façade often includes a case, and invariably some number of pipes (even if they are non-speaking); an organ which is hidden behind a grille has no façade.

Fagotto [noun] - A moderate-to-small-scale chorus reed stop, equivalent to Bassoon, although the organ version is generally not imitative of the orchestral instrument. Usually found at 16' pitch in either manual or pedal divisions.

Fan Tremulant [noun] a type of tremulant which consists of a board rotating on a horizontal shaft, placed immediately above the pipework.


Fernwerk [noun] - German term for the English "Antiphonal."

Fifteenth [noun] - A diapason or principal stop found in the manuals at the 2' pitch level. Usually a part of the Great principal chorus.

Filled-In Shallot

Flat [noun] - A number of medium- or small-sized pipes arranged in a row on the facade of the organ case. Usually alternates with towers (q.v.) in a more-or-less symmetrical array. Often set in highly carved and/or decorated woodwork, particularly in early organs.

Flexible Wind

Floating Division - A group of stops that has no regular keyboard from which it is played, but which can be played from any keyboard via couplers. Typically found in large instruments with electrical actions. Example:an "Echo Division" on an organ with only Swell, Great, and Choir keyboards. Synonym: Ancillary Division.

Flue [noun] a type of organ pipe which produces sound in the manner of a whistle (fipple flute).

Foot [noun] the portion of a flue pipe between the mouth and the toe, of inverted conical shape in all but the smallest pipes.

Foundation Stop [noun] - Generic term for a principal, flute, or string stop on the manuals at 8' pitch. The French Romantic fonds always had a diapason, large-scale harmonic flute, string, and stopped flute drawn together, an indispensible resource for that literature.

Fourniture [noun] - A compound mixture stop composed of three or more high-pitched ranks, found as part of the chorus in a division. If there are two mixtures in the division, the Fourniture will likely be the lower-pitched of the two. The Fourniture is usually composed of octave- and fifth-sounding ranks, but has been constructed with thirds particularly in the 19th-century style.

Free Reed [noun] a reed or reed pipe in which the reed (tongue) vibrates within an opening, but does not beat against it. Compare with Beating Reed. Examples of free reeds are those used in: the accordion, the harmonica and the harmonium or "reed organ".

Frein Harmonique [noun] - The harmonic bridge, a clamp or rack-like device, or sometimes a wooden roller, mounted near the mouth of certain pipes to improve speech and intonation. It is used mainly on strings, but can also by found on the basses of some flute stops to help the pipe settle into its fundamental.

French Horn [noun] - A reed stop, found in large instruments, voiced to imitate the orchestral instrument. Usually requires a higher wind pressure for success.

Full Swell [noun] - A characteristic sound of the English romantic organ, with chorus reeds and mixtures (and foundations) enclosed in a swell box.  WIth the swell closed, the resulting controlled fury was exciting, particularly in a large resonant building.  It also became a vital part of the American Classic sound, although Donald Harrison often used French-style reeds on his instruments.


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