We don't have synonyms for old prussians yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are old prussian and old russian.
(N) :
Old Prussians, Baltic Prussians or simply Prussians(Old Prussian: prūsai; or Prußen; ; ; ; ; ) were a Baltic people that inhabited the region of Prussia, on the southeastern shore of the Baltic Sea between the Vistula Lagoon to the west and the Curonian Lagoon to the east.
(N) :
Old Prussians, Baltic Prussians or simply Prussians(Old Prussian: prūsai; or Prußen; ; ; ; ; ) were a Baltic people that inhabited the region of Prussia, on the southeastern shore of the Baltic Sea between the Vistula Lagoon to the west and the Curonian Lagoon to the east.