English

Noun

1. A small barrel of no certain dimensions. It may contain from 3 to 20 gallons.
2. A measure for liquids, as for wine, usually 18.5 gallons.

   1882, Again, by 28 Hen. VIII, cap. 14, it is re-enacted that the tun of wine should contain 252 gallons, a butt of Malmsey 126 gallons, a pipe 126 gallons, a tercian or puncheon 84 gallons, a hogshead 63 gallons, a tierce 41 gallons, a barrel 31.5 gallons, a rundlet 18.5 gallons. — James Edwin Thorold Rogers, A History of Agriculture and Prices in England, p. 205.

The rundlet is an archaic unit-like size of wine casks once used in Britain. It was equivalent to about 68 litres. It used to be defined as 18 wine gallons—one of several gallons then in use—before the adoption of the imperial system in 1824, afterwards it was 15 imperial gallons, which became the universal English base unit of volume in the British realm.