[] ( gal.) a unit for measuring liquid. In the UK it is equal to about 4.5 litres; in the US it is equal to about 3.8 litres. The UK measure is often referred to as an imperial gallon 加仑（液量单位，英制约等於 4.5 升，美制约等於 3.8 升。常用 imperial gallon 表示英制加仑）◆In the US, oil is measured in barrels of about 42 gallons, or 159 litres. 在美国，石油用大约 42 加仑或者 159 升的桶来计量。