feud

n. enmity, vendetta, antagonism, continuing conflict (especially between families); row, argument

v. be involved in a bitter and lengthy quarrel

A feud is a long-running argument or fight between parties—often, through  guilt by association, groups of people, especially families or clans. Feuds tend to begin because one party (correctly or incorrectly) perceives itself to have been attacked, insulted or wronged by another. A long-running cycle of retaliation, often involving the original parties' family members and/or associates, then ensues. Feuds can last for generations.
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FIEF or FEUD - In its origin, a fief was a district of country allotted to one of the chiefs who invaded the Roman empire as a stipend or reward; with a condition annexed that the possessor should do service faithfully both at home and in the wars, to him by whom it was given. The law of fiefs supposed that originally all lands belonged to lords, who had had the generosity to abandon them to others, from whom the actual possessors derive their rights upon the sole reservation of certain services more or less onerous as a sign of superiority. To this superiority was added that which gives the right of dispensing justice, a right which was originally attached to all fiefs and conferred upon those who possessed it, the most eminent part of public power. F. DE BURSA is a fee paid by Kings for military service to their vassals.

F. DE CAMERA are the revenues of the Royal chamber.

F. FRANCUM is a free fief, exempted from some or all service to the King.

F. LIGIUM is land held from the "primary lord," from the lord who came first in any obligations; land held of the King.
   

This entry contains material from Bouvier's Legal Dictionary, a work published in the 1850's.

Noun
1. a bitter quarrel between two parties
(hypernym) conflict, struggle, battle
(hyponym) vendetta, blood feud
Verb
1. carry out a feud; "The two professors have been feuding for years"
(hypernym) fight, struggle

feud