rancourn.

rancourrancour: [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.=> rancidrancour (n.)chiefly British English spelling of rancor; for ending see -or. Related: Rancourous.