"fleet of warships," 1530s (armado), from Spanish armada "an armed force," from Medieval Latin armata "armed force" (see army). Current form of the word is from 1590s. The fleet sent by Philip II of Spain against England in 1588 was being called the Spanish Armada by 1613, the Invincible Armada by 1632.
arithmomania
Arizona
ark
Arkansas
arm
armada
armadillo
Armageddon
armament
armamentarium
armature