barrel

[derekleffew]

1. General. A large, cylindrical-shaped container. If made of wood, has curved sides made of staves.
2. General. As a measurement of petroleum product, equivalent to 42 US gallons.
3. Lighting. Portion of an ERS or profile spot that surrounds the lens tube.
4. A/V. A turnaround, usually female-female, used to join two male-male cable ends together for a longer run. "RJ45 barrel," "NL4, NL8 barrel," "BNC barrel," et al.

5. UK term. A height-adjustable horizontal lighting position in a TV/film studio, usually a two to five meter long electric batten with raceway.
From http://www.tvstudiohistory.co.uk/old bbc studios.htm :

[FONT=Verdana,Arial,Times New I2]Following the colourising of the studio it was equipped as follows:[/FONT]
[FONT=Verdana,Arial,Times New I2]24 motorised lighting hoists with barrels 4ft, 6ft and 10ft long depending on their position in the studio[/FONT]

LightingAudioVideoCarpentryA/VIT