Meaning

noun all the weapons and equipment that a country has

noun a military structure where arms and ammunition and other military equipment are stored and training is given in the use of arms

noun a place where arms are manufactured

originFrom Italian arsenale, from Arabic دَار الصِّنَاعَة (dār aṣ-ṣināʕa, “manufacturing shop”), from دَار (dār) + صِنَاعَة (ṣināʕa).

Etymology from Wiktionary, CC BY-SA 3.0