Of Gadara, a town in ancient Palestine near the Sea of Galilee.
With reference to, or in the context of, the story of the Gadarene swine related in Matthew 8:28–34, in which Jesus cures two men possessed by demons by allowing the spirits to enter a herd of pigs, which rush down a steep hillside and drown in the water below.
Mid 17th century; earliest use found in Richard Younge (fl. 1636–1673), religious writer. From the name of Gadara + -ean, perhaps as alteration of Gadarene.