canvas-back (n.)youdaoicibaDictYouDict[canvas-back 词源字典]
also canvasback, 1785 as a type of North American duck. Earlier as an adjective for a type of garment made of expensive stuff in front and cheap canvas in the back (c. 1600); from canvas (n.) + back (n.).[canvas-back etymology, canvas-back origin, 英语词源]