rancouryoudaoicibaDictYouDict[rancour 词源字典]
rancour: [14] To account for rancour and its close relative rancid we have to postulate a Latin verb *rancēre ‘stink’, never actually recorded but inferable from its present participle rancēns ‘stinking, putrid’. From it were derived the adjective rancidus, source of English rancid [17], and in post-classical times the noun rancor, source of English rancour.
=> rancid[rancour etymology, rancour origin, 英语词源]