imperial gallon(n = noun.quantity) congius, gallon - a British imperial capacity measure (liquid or dry) equal to 4 quarts or 4.545 liters;
is a kind of british capacity unit, imperial capacity unit
is a part of barrel, bbl, bushel, firkin
has parts: quart

british imperial system, crown imperial, gallon, imperial, imperial beard, imperial capacity unit, imperial decree, imperial elephant, imperial japanese morning glory, imperial mammoth, imperial moth, miles per gallon