bellows

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An apparatus for producing a strong current of air, as for sounding a pipe organ or increasing the draft to a fire, consisting of a flexible, valved air chamber that is contracted and expanded by pumping to force the air through a nozzle.
2. n. Something, such as the pleated windbag of an accordion, that resembles this apparatus.
3. n. The lungs.

Century Dictionary and Cyclopedia

1. An instrument or machine for producing a current of air: principally used for blowing fire, either in private dwellings or in forges, furnaces, mines, etc.; also used in organs for producing the current of air by which the pipes and reeds are sounded. It consists essentially of an air-chamber which can be alternately expanded and contracted, and a nozle by which the current of air can be directed. When the air-chamber is expanded, air is admitted through a valve opening inward. The pressure produced by the contraction of the air-chamber closes this valve, and leaves the nozle the only available avenue of escape for the air in the chamber. Bellows are made in many different forms, a usual one being the small hand-bellows, an ornamented example of which is shown in the cut, used for promoting the combustion of a house-fire. Bellows of great power are called blowing-machines, and are operated by machinery driven by steam.
2. In photography, that part of a camera which connects the front and back portions and is capable of being extended or closed as desired.
3. In organ-building, the extensive apparatus by which air is supplied and compressed for the sounding of the pipes. It usually includes two distinct parts, an oblique bellows, or feeder (resembling the ordinary household bellows, but on a large scale), by which the air is pumped into the reservoir, and a reservoir, called the storage-bellows, which is a horizontal bellows (having its top and bottom boards parallel and connected by creased folds of leather) so loaded by blocks of lead or other weights that the air within is maintained at a constant compression or tension. From the reservoir lead off the wind-trunks by which the compressed air is supplied to all parts of the instrument. Furthermore, on the wind-trunks are usually placed small bellows with springs, called concussion-bellows, panting-bellows, or winkers, by which sudden irregularities in pressure are taken up and counteracted.

Wiktionary

1. n. A device for delivering pressurized air in a controlled quantity to a controlled location. At its most simple terms a bellows is a container which is deformable in such a way as to alter its volume which has an outlet or outlets where one wishes to blow air.
2. n. Any flexible container or enclosure, as one used to cover a moving joint.
3. n. The lungs.
4. n. photography Flexible, light-tight enclosures connecting the lensboard and the camera back.
5. n. Plural form of bellow.
6. v. Third-person singular simple present indicative form of bellow.

GNU Webster's 1913

1. n. An instrument, utensil, or machine, which, by alternate expansion and contraction, or by rise and fall of the top, draws in air through a valve and expels it through a tube for various purposes, as blowing fires, ventilating mines, or filling the pipes of an organ with wind.

WordNet 3.0

1. n. a mechanical device that blows a strong current of air; used to make a fire burn more fiercely or to sound a musical instrument