I don't have an authoritative answer, either, but I would have thought it came from the days of sailing ships. Dutch ships tended to be flatter-bottomed than British or French and to have shorter keels (think of all those shallow harbours in Holland) and so, in open water, would roll more. I suspect that the term would have been transferred across to aviation in the early years, along with port, starboard, fore-and-aft, athwartships, cargo, hold, drift, and many others.