"putrefaction or necrosis of soft tissues," 1540s, cancrena, from Latin gangraena (Medieval Latin cancrena), from medical Greek gangraina "an eating or gnawing sore," literally "that which eats away," dissimilated reduplicated form of gran- "to gnaw," from PIE root *gras- "to devour" (see gastric).[gangrene etymology, gangrene origin, 英语词源]