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.
Mandrel [noun] - a wooden or metal cylinder or cone used for forming pipe metal into shape for making organ pipes.
Manometer [noun] a device for measuring wind pressure, consisting of a U-shaped tube partly full of water. The wind pressure is measured by the displacement of the water by the wind, and expressed in inches or millimeters.
Manual [noun] a keyboard played with the hands.
Mechanical Action [noun] any type of key or stop action in which there is a direct mechanical connection between the key or stop controls and the windchests. The term implies no use of electricity in the action, but generally is not used to include tubular-pneumatic action. Synonym: tracker action.
Melodia [noun] - An open wood flute stop of moderate scale and volume. Favored by American builders of the nineteenth and early twentieth centuries, it is fairly neutral in tone, and almost always found at the 8' pitch level.
Mitre [verb] To cut a pipe at an angle and cause it to go around a corner. Usually done to make a tall pipe fit in a shorter space.
Mixture [noun] - A compound stop of 2 or more high-pitched ranks, generally comprised of principal-tone pipes and breaking back to lower octaves as the scale ascends. Mixture is the generic term as well as a stop name. In American usage, the mixture usually has unison- and fifth-sounding ranks, but some have thirds as well. Mixtures are the upper completion of the principal chorus and are a remnant of the old Blockwerk.
Möller, M. P., Inc. [noun] Prolific American organ building firm, active from 1875-1992. They had surpassed opus no. 11,700 by the time they ceased operations.
Monkey Quint [noun] - A polyphone stop in which the pipes are constructed to sound the unison and the quint together using separate airways in a single pipe structure. The shorter quint-sounding pipe is piggy-backed onto the side of the longer unison-sounding portion, looking to some like a monkey climbing tree-trunk. Thus, "Monkey Quint". It is only a curiosity in modern times.
Mouth [noun] the open area of a flue pipe framed by the upper and lower lips, which are usually considered to be part of the mouth. The width of the mouth is usually expressed as a fraction of the pipe's circumference.
Mutation [noun] - an organ stop that speaks at a pitch other than unison or octave. This term is sometimes used to include 1' stops as well.