unhealthy (adj.)youdaoicibaDictYouDict[unhealthy 词源字典]
1590s, "injurious to health," from un- (1) "not" + healthy (adj.). Earlier unhealthsome (1540s), unhealthful (1570s). Of persons, "sickly," it is attested from 1610s. Related: Unhealthily.[unhealthy etymology, unhealthy origin, 英语词源]