chronic (adj.)youdaoicibaDictYouDict[chronic 词源字典]
early 15c., of diseases, "lasting a long time," from Middle French chronique, from Latin chronicus, from Greek khronikos "of time, concerning time," from khronos "time" (see chrono-). Vague disapproving sense (from 17c.) is from association with diseases and later addictions.[chronic etymology, chronic origin, 英语词源]