"large cask or barrel," late 14c., presumably on some perceived resemblance or some mark formerly borne by the casks. The liquid measure was fixed at 63 (old) wine gallons (by a statute of 1423); later and for other liquids anywhere from 100 to 140 gallons. Borrowed into other Germanic languages, inexplicably, as ox-head (Dutch okshoofd, German oxhoft, Swedish oxhufvud). English might have gotten the word from them, but the forms of the Continental words suggest the reverse. English pig "container for wine" is attested from mid-15c., perhaps from the hide of a pig used as a wineskin, but the connection is obscure.
updated on June 08, 2020