/ ˈgælən; NAmE / noun
( abbr. gal. ) a unit for measuring liquid. In the UK, Canada and other countries it is equal to about 4.5 litres; in the US it is equal to about 3.8 litres. There are four quarts in a gallon.
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WORD ORIGIN
Middle English : from Anglo-Norman French galon , from the base of medieval Latin galleta , galletum pail, liquid measure, perhaps of Celtic origin.