We don't have synonyms for thessalonica yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are thessalonika, thessalonian and thessaloniki.
(n) :
(now especially historical) Alternative form of Thessaloniki: a port city, the capital of Central Macedonia, in northern Greece. [A port city, the capital of Central Macedonia, in northern Greece.]
(n) :
(now especially historical) Alternative form of Thessaloniki: a port city, the capital of Central Macedonia, in northern Greece. [A port city, the capital of Central Macedonia, in northern Greece.]