"an armory," 1874, Latin, literally "little arsenal," from armamenta "implements, weapons" (see armament). Earlier Englished as armamentary (1731).
Entries linking to armamentarium
armament n.
1650s, "naval force equipped for war," from Latin armamentum "implement," from Latin armare "to arm, furnish with weapons" from arma "weapons" (including defensive armor), literally "tools, implements (of war);" see arm (n.2). The meaning "process of equipping for war" is from 1813.