: the period of time during which a king, queen, emperor, etc., is ruler of a country
: the period of time during which someone is in charge of a group or organization
: the period of time during which someone or something is the best or the most important, powerful, etc.
: to rule as a king, queen, emperor, etc.
: to be the best or the most powerful or important person or thing
—used to say that a quality exists to such a degree in a place or situation that it affects everything about that place or situation
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