origin unknown, but thot to perhaps be from the Gaulish.

Origin: 1250–1300; ME barell < AF baril, OF barril < VL *barrīculum, equiv. to *barrīc(a), perh. deriv. of LL barra bar1 + L -ulum -ule; cf. ML (ca. 800) barriclus small cask

today, in digi-text and cell fone jargon it means 'be back later'