kingship: the power, period, and realm of a king, and the things that belong to him as king
This word is the abstract noun built from the verb "to be king." At its center is the fact of ruling as a king: holding royal power. From that center the word reaches in three natural directions, and the same form covers all of them.
First it names royal power itself, the right and reign of the one who sits on the throne. Used of God, it is His sovereignty over everything that exists (Psalm 103:19, 145:11-13). Used of a human king, it is the rule God grants and establishes (1 Chronicles 17:14).
From "reign as power" the word slides easily to "reign as a span of time," which is why the history books and Daniel keep dating events to a given year of a king's rule. It also widens to the territory and people a king rules, his kingdom as a place (Daniel 8:22; Esther's empire stretching across its provinces).
Finally, especially in Esther, the word works as a label meaning "royal," marking whatever pertains to the king: his crown, his estate, his wine, his palace. These are not separate words but one word doing the ordinary work an abstract noun does, naming the office and then everything that flows from it.