We don't have synonyms for uniters yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are uniter, unites and uniterm.
(n) :
(UK, historical) A British gold coin worth 20 shillings, first produced during the reign of King James I, and bearing a legend indicating the king's intention of uniting the kingdoms of England and Scotland.
(n) :
(UK, historical) A British gold coin worth 20 shillings, first produced during the reign of King James I, and bearing a legend indicating the king's intention of uniting the kingdoms of England and Scotland.