1) A gold coin of varying value that was formerly in use in most European countries (OED).
Yorkshire references noted so far are all to 'double' ducats: 1543 unto whom I sende a dubbyll duckett,/i>, Brettanby
1562 to my Mrsone doble dicate, Lindley
1570 Item in golde 6 double ducketes, Spaldington
1582 I will geve ... to my good mres Mres Wandesforde one duble duckett, Hudswell.