Webster's Revised Unabridged Dictionary
F. or Sp. ducaton, fr. ducat,
Chambers's Twentieth Century Dictionary
O. Fr. ducat—It. ducato—ducatus, a duchy. The name was applied to an Apulian silver coin of 1140. The first gold ducat struck at Venice in 1284 bore the legend—'Sit tibi Christe datus quem tu regis iste Ducatus' ('Be this duchy, which thou rulest, dedicated to thee, O Christ'), which may have helped to spread the name, though it did not originate it.
DUCATOON', formerly a Dutch silver coin worth 3 gulden 3 stivers, or 5s.
"The New Gresham Encyclopedia" by Various
The boatmen they paid some L7000, and threw them handfuls of ducatoons to scramble for.
"The Monarchs of the Main, Volume III (of 3)" by Walter Thornbury