opaque (adj.)youdaoicibaDictYouDict[opaque 词源字典]
early 15c., opake, from Latin opacus "shaded, in the shade, shady, dark, darkened, obscure," of unknown origin. Spelling influenced after c. 1650 by French opaque (c. 1500), from the Latin. Figurative use from 1761. Related: Opaquely; opaqueness.[opaque etymology, opaque origin, 英语词源]