late 14c., from O.Fr. ducat
, from It. ducato
, from M.L. ducatus
"coin," originally "duchy," from dux
) "duke" (see duke
). So called for the name or effigy of Roger II of Sicily, Duke of Apulia, which first issued the coins (c.1140). The legend on them read, "Sit tibi, Christe, datus, quem tu regis, iste ducatus."
Byzantine emperor Constantine X had the Gk. form doux
struck on his coins during his reign (1059-1067). Over the years it was a unit of currency of varying value in Holland, Russia, Austria, Sweden, Venice, etc. Remained popular in slang for "money" or "ticket" from its prominence in "The Merchant of Venice."