gallon
A unit of volume; in Japan usually the US gallon (approx. 3.785 liters) or the British imperial gallon (approx. 4.546 liters). Context often clarifies which gallon is meant.
This tank holds 10 gallons of water.
Please put in 5 gallons of gasoline.
In America, milk is often bought by the gallon.
This car gets 30 miles per gallon.
Loanword from English 'gallon', borrowed into Japanese as ガロン.