ENGLISH
REFERENCE

gallon

n.
US //ˈɡæɫən// UK //ɡˈælən// gal·lon
  1. 1 unit of volume (n.)
    B1 Intermediate

    a unit for measuring liquids. In the US, it is about 3.8 litres, and in the UK, it is about 4.5 litres.

    a unit of liquid volume. The US liquid gallon is defined as 231 cubic inches, whereas the imperial gallon is defined as 4.54609 litres.

    Example

    The car's tank holds about twelve gallons of petrol.

    Example

    With fuel prices rising, many commuters are calculating exactly how many miles they can get out of a single gallon of petrol.

    Usage

    Often used when talking about fuel or milk.

  2. 2 large amount (n.)
    C1 Advanced Informal

    a very large amount of a liquid.

    a large quantity of liquid, used figuratively in the plural to emphasise volume.

    Example

    We drank gallons of water after our long hike in the sun.

    Example

    The children managed to spill gallons of paint across the new carpet before anyone noticed what they were doing.

    Usage

    Almost always used in the plural form 'gallons'.
Origin

From Middle English gallon, galoun, galun, from Old Northern French galun, galon (“liquid measure”) (compare Old French jalon), from Late Latin galum, galus (“measure of wine”), from Vulgar Latin galla (“vessel”), possibly from Gaulish galla, ultimately from Proto-Indo-European *kel- (“goblet”). Cognate with Ancient Greek κύλιξ (kúlix, “cup”), Sanskrit कलश (kalaśa, “jar, pitcher; measure of liquid”). Related to Old French gille (“wine measure”) (from Medieval Latin gillō (“earthenware jar”)), Old French jale (“bowl”), Old French jaloie (“measure of capacity”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Last updated June 20, 2026