An Etymological Dictionary of the German Language/Annotated/Back
Back, neuter, ‘a deep wooden dish, in which food is served for a certain number of the crew’; borrowed, like many technical terms of sea-life, from Low German; Low German back, ‘dish,’ English back (‘tub, vat’); compare Modern French bac, ‘brewer’s vat or tub,’ borrowed from this word or the Dutch bak. It has been derived from Late Latin bacca, ‘water vessel,’ whence also French bac, ‘ferryboat,’ Dutch bak, English bac, ‘a flat-bottomed boat.’ Probably Becken is allied to it.