SIESWERDA / SIJSWERDA / SYSWERDA : All are the same last name. Spelling variations are Dutch or Fries in the names Sieswerda or Sijswerda. The "ij" = "y" in the modern spelling of Sijswerda = Syswerda.
Sies/Sijs is a mans name in Fries. It means 'Victory' when translated to English. Werd or Wird is an "old Frisian' word for 'Height' or a 'High Place'. 'Sies Werd' would therefore refer to Sies's High Place. Friesland was regularly flooded by the North Sea so it was necessary to find or build high places for farm homes and buildings, churches, and towns.
The name originates from Friesland and is connected to Farms (there were 4 of them at various times ) all very near to Hichtum. The farms were substantial enough to have the name Sieswerd/Sijswerd. Old maps show the names as "Sieswerd" and "Sijswerd" depending on who had made the map and at what time period.
Ancestor Bauke Jentjes appears to have already been living at the Farm Sieswerd when he got married. Sometime between 1738 and 1748 he became the head farmer of Sieswerd/Sijswerd. He became known as Bauke Jentjes van Sieswerd/Sijswerd. [http://www.burgwerd-hichtum.nl/ Under 'historie' see Sieswerd.
In 1811, following the decrees of Napoleon, the Family had to take a permanent last name. The entire Family, whether they lived on the farms or in the surrounding villages and towns, chose "Sieswerda/Sijswerda". The spellings varied as to where they registered and who did the registering. Some registrars were Dutch and others Fries.
The Family "Coat of Arms"
At the top is a Frisian Horse representing the Farming Heritage of the Family. On the left side of the shield is the Frisian 'Half Eagle' representing the Freedom held so dear by the Frisian people. On the right side of the shield is a Sword. The Frisian name Sies/Sijs means the equivalent in English to "Victory". Thus the Sword of Victory. At the top of the right side of the shield are two Lilies. The Lilies are an old symbol representing the Virgin Mary. One Lily represents Hichtum/Sieswerd and the other Pingjum. These were the two major ancestral homes of the Family. The colors Green and Gold were also 'borrowed' from the Coats of Arms of Hichtum/Sieswerd and Pingjum. The colors are also equivalent to the families farming history: Green for growth and Gold for harvest.
There is still a Farm (Sieswerd) at Hichtum and a road that is named Sieswerd. The present day farm is owned by other folks.