firkin

From Middle Dutch *vierdekijn, diminutive of vierde (“fourth”),[1] from vier (“four”), equivalent to fourth +‎ -kin.

• (US) IPA^(key): /ˈfɝkɪn/
• (Received Pronunciation) IPA^(key): /ˈfɜːkɪn/
• Rhymes: -ɜː(ɹ)kɪn

firkin (plural firkins)

1. (Britain) A varying measure of capacity, usually being the fourth part of a barrel; specifically, a measure equal to nine imperial gallons.
   • 1882, James Edwin Thorold Rogers, A History of Agriculture and Prices in England, volume 4, page 205:

     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.

2. (US) A small wooden vessel or cask of indeterminate size, used for butter, lard, etc.
3. A weight measure for butter, equalling 56 pounds.

• Rifkin