Do you know ghouls from goblins and ghosts?
liquid measure, late 13c., from Old North French galon, corresponding to Old French jalon "liquid measure," related to jale "bowl," from Medieval Latin diminutive form galleta "bucket, pail," also "a measure of wine," of unknown origin, perhaps from Gaulish galla "vessel."
gallon gal·lon (gāl'ən)
A unit of volume in the U.S. Customary System, used in liquid measure, equal to 4 quarts, 231 cubic inches, or 8.3389 pounds of distilled water (3.7853 liters).
A unit of liquid volume or capacity in the US Customary System equal to 4 quarts (3.79 liters). See Table at measurement.