In its original Germanic use this word meant a king's or a lord's area of power or authority. Later, it signified a king's power to command and prohibit under pain of punishment or death, mainly used because of a breach of the *king's peace. Also, a royal proclamation, either of a call to arms, or a decree of outlawry; in clerical terms, *excommunication on condemnation by the Church.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.