Merriam-Webster Collegiate Dictionary - ecu

 I. noun  (plural ~s)  Etymology: Middle French, literally, shield, from Old French escu, from Latin scutum; from the device of a shield on the coin — more at esquire  Date: circa 1593 any of various old French units of value; also a coin representing an ~  II. noun  Usage: often capitalized E&C&U  Etymology: European Currency Unit (influenced by French ecu ~)  Date: 1970 a money of account based on the currency units of members of the European Union from 1979 up to the introduction of the euro in 1999