gallon
n. countablen. a unit for measuring liquids, equal to about 3.8 liters in the US or 4.5 liters in the UK. People often use the plural form to mean a very large amount of something.
n. a unit of liquid capacity equal to four quarts. While primarily a technical measurement, the plural form is frequently used hyperbolically to indicate a vast quantity of liquid.
The car needs another gallon of gas to reach the city.
After the long hike in the summer heat, the thirsty group drank gallons of cold water.
Despite the engine's efficiency, the heavy load caused the truck to consume a gallon of fuel for every eight miles traveled across the mountain pass.
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”).
Commonly used with the preposition 'of' when followed by a specific substance.