Gallon n. : A measure of capacity, containing four quarts; -- used, for the most part, in liquid measure, but sometimes in dry measure.

Example:
How can you measure 4 Gallons of water into the 5 Gallon bucket?

Taxonomy
Imperial gallon, gallons, in3, definitions, corn, liquid gallon, wine gallon, Exchequer, cu in, 01-15, fuel, the United Kingdom, pint, wine, density, Belize, price of gasoline, free encyclopedia.

Defination from the web:
gallon. ... As of 2005 the U.S. liquid gallon continued to be used as a unit of measure for fuel in Colombia, Dominican Republic, Ecuador, El Salvador, ...