Why is the ninth month called September?
late 14c., "warlike munitions," from Anglo-French artillerie, Old French artillerie (14c.), from artillier "to provide with engines of war" (13c.), which probably is from Medieval Latin articulum "art, skill," diminutive of Latin ars (genitive artis) "art." But some would connect it with Latin articulum "joint," and still others with Old French atillier "to equip," altered by influence of arte. Sense of "engines for discharging missiles" (catapults, slings, bows, etc.) is from late 15c.; that of "ordnance, large guns" is from 1530s.
1 Sam. 20:40, (Heb. keli, meaning "apparatus;" here meaning collectively any missile weapons, as arrows and lances. In Revised Version, "weapons"). This word is derived from the Latin artillaria = equipment of war.