a kingdom: either the concrete realm of a king (territory, nation, political domain) or the authority and institution of royal rule itself
The word covers the full range that English "kingdom" covers: from specific territories and nations governed by kings, to the royal office and sovereign authority a king exercises. Most occurrences are concrete, naming a particular political entity, the kingdom of Sihon, the kingdoms of Canaan, the kingdoms of the earth. But the same word also names the institution of rule, the ongoing reign a dynasty sustains or loses.
The concrete and abstract senses shade into each other naturally. When the prophets speak of God overturning "the kingdoms" (Haggai 2:22), they mean the nations and their thrones together, territorial dominion and royal power as one thing. When God promises David an everlasting kingdom (2 Samuel 7:12-16), he is pledging the enduring institution of royal rule, not a fixed piece of geography. Israel itself is called "a kingdom of priests" in Exodus 19:6, naming a vocation and a status, not a land.
The word is close in meaning to two related nouns: H4438 (מַלְכוּת), which leans toward the dignity and exercise of royalty, and H4410 (מְלוּכָה), which names kingship as a status or office. H4467 by contrast is the most common of the three and tends toward the political entity, the organized realm, nation, or power, as much as toward the abstract quality of ruling.