Final answer:
A government operated by a single person until they die or abdicate is known as a monarchy.
Step-by-step explanation:
A government run by a single individual until death or abdication is called a monarchy. A monarch, who is usually a king or queen, heads this form of government, often holding power through hereditary succession or divine appointment. In a monarchy, the ruler's position is typically for life, unless they give up their role through abdication.
Monarchies can vary significantly in their expression of power. Some countries operate under absolute monarchies where the monarch holds unmitigated power to legislate, tax, and govern as they see fit. Conversely, other nations may have constitutional monarchies in which the monarchs serve largely ceremonial roles, with actual governance conducted within the bounds of a constitution.