BARREL

(1) A measure of liquid volume (conventionally) equal to 42 U.S. gallons (34.9723 Imperial gallons), or 158.9873 liters. (2) Any of various units of volume or capacity. In the U.S. Customary System, it varies, as a liquid measure, from 31 to 42 U.S. gallons (approximately 120 to 159 liters) as established by law or usage.