repellent (adj.)youdaoicibaDictYouDict[repellent 词源字典]
also repellant, 1640s, from Latin repellentem (nominative repelens), present participle of repellere (see repel). Originally of medicines (that reduced tumors); meaning "distasteful, disagreeable" first recorded 1797.[repellent etymology, repellent origin, 英语词源]
repellent (n.)youdaoicibaDictYouDict
also repellant, 1660s, "medicine that reduces tumors," from repellent (adj.). As "substance that repels insects," 1908.