gallon

Etymology

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 [Term?], 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”).

noun

1. A unit of volume, equivalent to eight pints
2. (Britain, Canada) exactly 4.54609 liters; an imperial gallon
3. (US) 231 cubic inches or approximately 3.785 liters for liquids (a "U.S. liquid gallon")
4. (US) one-eighth of a U.S. bushel or approximately 4.405 liters for dry goods (a "U.S. dry gallon").
5. (in the plural, informal) A large quantity (of any liquid).
   The pipe burst and gallons of water flooded into the kitchen.