A feud is a long-lasting, bitter conflict between two people, families, or groups who keep fighting or arguing over something that happened in the past. Unlike a simple disagreement that gets resolved quickly, a feud drags on because each side refuses to forgive or forget, often seeking revenge for wrongs done to them.

One of the most famous feuds in American history involved two families, the Hatfields and McCoys, who fought for decades along the Kentucky-West Virginia border in the late 1800s. What started as disputes over property and a pig eventually spiraled into violence and hatred that lasted for generations. Literary history's most famous feud appears in Shakespeare's Romeo and Juliet, where two families, the Montagues and Capulets, carry on a bitter feud that ultimately destroys them both.

Feuds can happen on smaller scales too. Two classmates might develop a feud if they constantly compete and hold grudges against each other, or two neighbors might feud over where a property line should be drawn. The word can be used as a verb: when people feud, they're actively maintaining their conflict rather than trying to resolve it.

What makes a feud different from an ordinary argument is its endurance and bitterness. Arguments end; feuds continue, sometimes outlasting the people who started them, as children inherit their parents' resentments without even knowing what originally caused the trouble.