a private feud in which the members of the family of a murdered person seek to avenge the murder by killing the slayer or one of the slayer's relatives, esp. such vengeance as once practiced in Corsica and parts of Italy.

any prolonged and bitter feud, rivalry, contention, or the like

a political vendetta.

noun

argument , bad blood * , bickering , conflict , disagreement , discord , dispute , dissension , falling out , family feud , fight , fracas , grudge , hostility , quarrel , revenge , rivalry , row , squabble , strife , feud , gripe