What is the after sail of a ship or bark, being a fore-and-aft sail attached to a boom and gaff; -- sometimes called driver. See Illust. under Sail. Totten called?

spanker — (Naut.) The after sail of a ship or bark, being a fore-and-aft sail attached to a boom and gaff; -- sometimes called driver. See Illust. under Sail. Totten. (Webster's 1913.)

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