Already attested as Latin dorna (“trough; concave”) in local 10th-century Latin charters. From a substrate language, from *dru-no- (“trough”), from Proto-Indo-European *dóru (“tree”). Alternatively from Proto-Celtic *durnos (“fist, hand”) (compare Breton dorn, Irish dorn); the word could have been first a unit of length, later becoming a unit of volume and a container, and later a ship, or either it was a reference to the concavity of the hand. Cognate with Spanish duerna, Occitan dorna and French dorne.