- (US) 231 cubic inches or approximately 3.785 liters for liquids (a "U.S. liquid gallon")
- (Britain, Canada) exactly 4.54609 liters; an imperial gallon
- (in the plural, informal) A large quantity (of any liquid).
"The pipe burst and gallons of water flooded into the kitchen."
- A unit of volume, equivalent to eight pints
- (US) one-eighth of a U.S. bushel or approximately 4.405 liters for dry goods (a "U.S. dry gallon").