We don't have synonyms for achaia yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are achaea, achara and achia.
(n) :
Alternative form of Achaea. [An ancient region in the northern part of the Peloponnese peninsula, Greece, occupying the coastal strip north of Arcadia, containing mostly mountains.]
(n) :
Alternative form of Achaea. [An ancient region in the northern part of the Peloponnese peninsula, Greece, occupying the coastal strip north of Arcadia, containing mostly mountains.]