From Longman Dictionary of Contemporary Englishgallongal‧lon /ˈɡælən/ ●●● S3 W3 noun [countable] 1 (written abbreviation gal)TM a unit for measuring liquids, equal to eight pints. In Britain this is 4.55 litres, and in the US it is 3.79 litres a 20-gallon fish tank The car does about 50 miles per gallon.2 informal a lot of a liquid We drank gallons of coffee.
Examples from the Corpusgallon• A 34 gallon fuel tank was placed below the cabin floor.• This model is the 1000 suitable for tanks to 80 gallons or 1000 gallons ponds.• Unleaded gasoline for February delivery fell 1. 83 cents to 58. 65 cents a gallon.• Last Friday, heating oil futures rose 2. 3 percent a gallon in New York to 60. 64 cents.• a gallon of water• The flow of metal-contaminated water is now four million gallons a day, of which 3.3 million gallons are treated.• A friend of hers, who also owns an Insight, reports getting 75 to 80 miles per gallon.• Believe me, it gets far more productivity to the gallon!miles per gallon• But while the turbo provides the poke, the diesel factor ensures economic consumption of around 47 miles per gallon.• A friend of hers, who also owns an Insight, reports getting 75 to 80 miles per gallon.• Understand and use simple rates; e.g. £ per hour, miles per gallon.• The Volkswagens of 1970 did not get as many miles per gallon as the Cadillacs of today do.• Taking age into account and the lack of accuracy possible when measuring miles per gallon, 15 is not a bad score!• And, the six-cylinder gets two more miles per gallon of premium fuel than does the V-8.• Fill it up with diesel, and it should reward you with a return of comfortably over miles per gallon on average.• I want to retain the present engine's performance but increase the miles per gallon.From Longman Business Dictionarygallongal‧lon /ˈgælən/ noun [countable]1British English a unit for measuring liquids, equal to 4.5435 litresA price increase of 2p on a litre of petrol is equal to a rise of more than 9p a gallon.a 12.6 million-gallon cargo of industrial oil2American English a unit for measuring liquids, equal to 3.785 litresThe average price of unleaded gasoline has now risen to over $3 a gallon.An improvement in car mileage of just one mile per gallon would save 350,000 barrels of crude oil per dayOrigin gallon (1200-1300) Old North French Medieval Latin galeta “liquid container, liquid measure”