c. 1500, "dockyard, dock with naval stores," from Italian arzenale, from Arabic dar as-sina'ah "workshop," literally "house of manufacture," from dar "house" + sina'ah "art, craft, skill," from sana'a "he made."
The word was applied by the Venetians to a large wharf in their city, and English picked it up in this sense. The meaning "public place for making or storing weapons and ammunition" is from 1570s. The London football club (1886) was named for the Royal Arsenal, Woolwich, where the original players worked.