vendetta(n = noun.act) blood feud - a feud in which members of the opposing parties murder each other;
is a kind of feud

1.  A blood feud; private revenge for the murder of a kinsman. [1913 Webster]

2.  Any feud or contention that is bitter and prolonged; however, the deep enmity may be held by only one party to the dispute; as, the former Mayor nurtured a lifelong vendetta against the candidate who defeated him. [PJC]

vendetta, n.
1 a a blood feud in which the family of a murdered person seeks vengeance on the murderer or the murderer's family. b this practice as prevalent in Corsica and Sicily.
2 a prolonged bitter quarrel.

Etymology:
It. f. L vindicta: see VINDICTIVE

N  revenge, revengement, vengeance, avengement, avengeance, sweet revenge, vendetta, death feud, blood for blood retaliation, day of reckoning, rancor, vindictiveness, implacability, malevolence, ruthlessness, avenger, vindicator, Nemesis, Eumenides, revengeful, vengeful, vindictive, rancorous, pitiless, ruthless, rigorous, avenging, unforgiving, unrelenting, inexorable, stony-hearted, implacable, relentless, remorseless, aeternum servans sub pectore vulnus, rankling, immitigable, manet ciratrix, manet alid mente repostum, dies irae dies illa, in high vengeance there is noble scorn, inhumanum verbum est ultio, malevolus animus abditos dentes habet, now infidel I have thee on the hip.