from French diphthérie, coined 1857 by physician Pierre Bretonneau (1778-1862) from Greek diphthera "prepared hide, leather," which is of unknown origin; the disease so called for the tough membrane that forms in the throat. Bretonneau's earlier name for it was diphthérite, anglicized as diphtheritis (1826). Formerly known in England as the Boulogne sore throat, because it spread from France.