ecu (n.)

old French silver coin, 1704, from French écu, "a shield," also the name of a coin, from Old French escu (12c.) "shield, coat of arms," also the name of a coin with three fleur-de-lys stamped on it as on the shield, formerly escut, from Latin scutum "shield" (see escutcheon). First issued by Louis IX (1226-1270); so called because the shield of France was imprinted on them.