Arsenal/ˈɑːrsənl/ Definition 1 of 3Pro Tip 1/3Military Origin Originally used for places storing military items, 'arsenal' keeps this strong association. The ancient arsenal contained cannons and swords. Pro Tip 2/3Not For Weapons 'Arsenal' isn't used for places that just sell weapons, like gun shops. He mistakenly called the gun shop an arsenal. Pro Tip 3/3Security Implications An 'arsenal' often implies a secure, controlled facility due to the dangerous items stored. The military arsenal was guarded 24/7.