Imperial gallon - a British imperial capacity measure (liquid or dry) equal to 4 quarts or 4.545 litersbbl, barrel - any of various units of capacity; "a barrel of beer is 31 gallons and a barrel of oil is 42 gallons" quart - a British imperial capacity measure (liquid or dry) equal to 2 pints or 1.136 liters bushel - a British imperial capacity measure (liquid or dry) equal to 4 pecks firkin - a British unit of capacity equal to 9 imperial gallons |