gallon//ˈɡælən//B1Frequency Level 9NeutralNoungallonSingulargallonsPlural1A unit of liquid capacity equal to four quarts, approximately 3.79 liters in the US and 4.55 liters in the UK.This car uses about two gallons of gas per day.2A large quantity of liquid, used informally.I drank gallons of water after the marathon.Synonymquartliter
