gallon
noun [ C ]
MEASURES uk/ˈɡælən/ us( abbreviation gal.)in the UK, a unit for measuring the volume of a liquid or gas, equal to approximately 4.55 litres:
Fuel tax is to rise by over 25p a gallon.
in the US, a unit for measuring the volume of a liquid, equal to approximately 3.79 litres:
The average federally set price of milk is expected to rise 42 cents, to $1.58 a gallon.