Kanly

The act of Kanly is the execution of a feud or fight under the rules of the Great Convention. Kanly is the formal, highly ritualized law governing blood feuds and vendettas between the noble Great Houses of the Imperium. In a universe where warfare could easily destroy entire planets, the Imperium created a constitution-like rulebook called the Great Convention to keep the peace. Kanly is a legal loophole within that convention. It allows two noble houses – like the Atreides and the Harkonnens – to declare an official, legal war of extermination against each other, but under strict rules. The most important rules of Kanly include:
No Nuclear Weapons – Using atomics against humans results in immediate planetary destruction by the other houses.
Protect the Innocent – The conflict must be carried out using precise assassinations, poison, or specialized duelists to minimize collateral damage to civilians and galactic trade.

Frank Herbert didn’t make this word up either. Kanly comes directly from the Turkish word kanli, which means “bloody” or “someone involved in a blood feud” (derived from kan, meaning blood). In historical Turkish tribal traditions, a kanli feud meant that a family was legally bound to seek vengeance from generation to generation until the debt of honor was paid in blood. By using this term, Herbert highlights the supreme irony of the futuristic Imperium – despite having space travel and energy shields, their high society is still driven by primitive, violent tribal blood feuds wrapped in polite corporate etiquette.