Final answer:
Sovereignty is the term that best matches the definition of 'the power of a state to rule itself.' It refers to complete and independent control over a territory.
Step-by-step explanation:
Sovereignty is the term that best matches the definition of 'the power of a state to rule itself.' It refers to complete and independent control over a territory, including the ability to make laws, enforce them, and maintain order within its borders. For example, in the case of a sovereign nation, the government has authority and autonomy over its land and people without interference from external forces.
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