gallon Meaning, Definition & Usage

  1. noun United States liquid unit equal to 4 quarts or 3.785 liters
    gal.
  2. noun a British imperial capacity measure (liquid or dry) equal to 4 quarts or 4.545 liters
    Imperial gallon; congius.

WordNet

Gal"lon noun
Etymology
OF galon, jalon, LL. galo, galona, fr. galum a liquid measure; cf. F. jale large bowl. Cf. Gill a measure.
Definitions
  1. A measure of capacity, containing four quarts; -- used, for the most part, in liquid measure, but sometimes in dry measure. ✍ The standart gallon of the Unites States contains 231 cubic inches, or 8.3389 pounds avoirdupois of distilled water at its maximum density, and with the barometer at 30 inches. This is almost exactly equivalent to a cylinder of seven inches in diameter and six inches in height, and is the same as the old English wine gallon. The beer gallon, now little used in the United States, contains 282 cubic inches. The English imperial gallon contains 10 pounds avoirdupois of distilled water at 62 of Fahrenheit, and barometer at 30 inches, equal to 277.274 cubic inches.

Webster 1913