1 a British unit of capacity equal to 9 imperial gallons
2 a small wooden keg
- Rhymes: -ɜː(r)kɪn
- A varying measure of capacity, usually being the fourth part of
a barrel; specifically, a measure equal to nine imperial gallons.
- 1882: 23 Hen. VIII, cap. 4... The barrel of beer is to hold 36 gallons, the kilderkin 18 gallons the firkin 9. But the barrel, kilderkin, and firkin of ale are to contain 32, 16, and 8 gallons. — James Edwin Thorold Rogers, A History of Agriculture and Prices in England, Volume 4, p. 205.
- A small wooden vessel or cask of indeterminate size, -- used for butter, lard, etc. [U.S.]
- A weight measure for butter, equalling 56 pounds.
A Firkin is an old English unit of volume. The name is derived from the Middle Dutch word vierdekijn, which means fourth, i.e. a fourth of a full-size barrel.
Nor need you mind the serial ordeal Of being watched from forty cellar holes As if by eye pairs out of forty firkins. — Robert Frost, "Directive"
For beer and ale a firkin is equal to nine imperial gallons or a quarter of a barrel (40.91481 litres). Casks in this size (themselves called firkins) are the most common container for cask ale.
For wine the firkin had a larger size, namely a third of a tun. A tun being 210 gallons in the UK and 252 fluid gallons in the US, thus a wine firkin is about 318 L (318.226 or 317.975). It is also called tertian or, preferably, puncheon (in the US also shortened to pon).
Butter and soap used to be sold by the firkin, too. In these cases it was rather a measure of mass, 56 lb (25.4 kg) and 64 lb (29.0 kg) respectively.
The term firkin is currently used to refer to antique wooden buckets, usually with wood handle and lid, about 10 inches (250 mm) high and 10 inches in diameter, formerly used to store sugar and other items.
The firkin (a firkin of water) is the base unit of mass in the humorous FFF System.
firkin in Russian: Феркин