We don't have synonyms for polonise yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are colonize, colonist and polonium.
(v) :
Non-Oxford British English standard spelling of Polonize. [(transitive) To make Polish as to custom, culture, language, or style; to adapt to the norms of the Republic of Poland.]
(v) :
Non-Oxford British English standard spelling of Polonize. [(transitive) To make Polish as to custom, culture, language, or style; to adapt to the norms of the Republic of Poland.]