Feud (noun)

1. A prolonged and bitter quarrel or dispute, especially between families or factions.
2. A state of long-standing mutual hostility.

Origin:

Feud (n) late middle english: from old french foide, from latin faida "hatred", from favere "speak well of".

Examples:

1. The feud between the two families had been going on for decades.
2. The feud between the two companies has affected the entire industry.
3. The feud led to a series of violent clashes.
4. Feuds are often based on jealousy and greed.
5. The feud was finally settled when the two parties came to an agreement.