A barrel organ (or roller organ) is a mechanical musical instrument consisting of bellows and one or more ranks of pipes housed in a case, usually of wood, and often highly decorated. The basic principle is the same as a traditional pipe organ, but rather than being played by an organist, the barrel organ is activated either by a person turning a crank, or by clockwork driven by weights or springs. The pieces of music are encoded onto wooden barrels (or cylinders), which are analogous to the keyboard of the traditional pipe organ.
There are many names for the barrel organ, such as hand organ, cylinder organ, box organ (though that can also mean a positive organ), street organ, grinder organ, and Low Countries organ. In French names include orgue à manivelle ("crank organ") and orgue de Barbarie ("Barbary organ"); German names include Drehorgel ("crank organ"), Leierkasten ("brace box"), and Walzenorgel ("cylinder organ"); Hungarian names include verkli (from Austrian-German Werkl), sípláda ("whistle chest") and kintorna (from Bayern-Austrian "Kinterne"); Italian names include organetto a manovella ("crank organ") and organo tedesco ("German organ") In Poland known as 'Katarynka'. While many of these terms refer to the physical operation of the crank, some refer to an exotic origin. The French name orgue de Barbarie, suggesting barbarians, has been explained as a corruption of the terms bara ("bread") and gwen ("wine") in Breton language, a false derivation from an Italian manufacturer from Modena, Giovanni Barberi or the English inventor John Burberry.
The term hurdy-gurdy is sometimes mistakenly applied to a small, portable barrel organ that was frequently played by organ grinders and buskers (street musicians), but the two terms should not be confused. Although the hurdy-gurdy is also powered by a crank and often used by street performers, it produces sound with a rosin-covered wheel rotated against tuned strings. Another key difference is that the hurdy-gurdy player is free to play any tune he or she desires, while the barrel organist is generally confined to pre-programmed tunes.