c.1300, "mail, defensive covering worn in combat," from O.Fr. armeure
(12c.), from L. armatura
"arms, equipment," from arma
"arms, gear" (see arm
(2)). The word might have died with jousting if not for late 19c. transference to metal-shielded machinery beginning with U.S. Civil War ironclads (first attested in this sense in an 1855 report from the U.S. Congressional Committee on Naval Affairs).