Gallon (noun)

1. A unit of measurement for liquid capacity equal to 4 quarts or 3.785 liters.
2. A container that holds a gallon of liquid.

Origin:

Middle english (denoting a measure of capacity): from old northern french galon, of germanic origin; related to german gallone.

Examples:

1. A gallon of milk weighs about 8.6 pounds.
2. He bought a gallon of gasoline for the car.
3. She poured a gallon of water into the pool.
4. The water tank can hold up to 5 gallons.
5. He needed a gallon of paint to finish the room.