Noah Webster's Dictionary (n.) A public establishment for the storage, or for the manufacture and storage, of arms and all military equipments, whether for land or naval service.

Multi-Version Concordance Arsenal (2 Occurrences) Song of Songs 4:4 Your neck is like the tower of David made for a store-house of arms, in which a thousand breastplates are hanging, breastplates for fighting-men. (See RSV) Jeremiah 50:25 Yahweh has opened his armory, and has brought forth the weapons of his indignation; for the Lord, Yahweh of Armies, has a work to do in the land of the Chaldeans. (See NIV)