ETYM From AS. feówer four (or an allied word, perh. Dutch or Danish) + -kin. Related to Four.
1. A British unit of capacity equal to 9 imperial gallons.
2. A small wooden barrel or cask.
Old unit of capacity equal to one quarter of a barrelsmall keg.
Small cask; measure of capacity: nine gallons.

ETYM Earlier cag, Icel. kaggi; akin to Swed. kagge.
1. Small cask or barrel.
2. The quantity contained in a keg; SYN. kegful.