The Hebrew aguddah means a bundle, cluster, band, or arch. It refers to things bound or vaulted together — a bundle of hyssop tied for the Passover, the vault of the earth, or a confederacy of troops.
The word's range — from a small bundle of hyssop to the great vault of the heavens — speaks to the principle of binding in Scripture. The hyssop bundle of the Passover (Exodus 12:22) applied the blood of the lamb to the doorpost, foreshadowing the blood of Christ that covers His people. The same root describes the "band" or "confederacy" of troops in Amos 9:6, where God builds His upper chambers in heaven and grounds His vault on the earth — sovereign over all alliances of nations.