worsen (v.)youdaoicibaDictYouDict[worsen 词源字典]
mid-13c., wersnen "to make worse," also "to grow worse," from worse (adj.) + -en (1). The reflexive sense of "to get worse, become worse off" was elevated into literary use c. 1800-30, where formerly worse (v.) had served. Related: Worsened; worsening.[worsen etymology, worsen origin, 英语词源]