n [ME barel, fr. MF baril] (14c) (1) The tubular main cylinder of an extruder, within which the screw rotates. (2) A container, agitated by rotation or vibration, used for tumbling moldings to remove flash and sharp edges. Also used for mixing of dry solids, e.g., pigments with resin pellets. (3) Standard unit of liquid volume in the petroleum industry. It is equal to 42 U.S. gallons, approximately 35 Imperial gallons; approximately 160 liters.