We don't have synonyms for galeas yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are galeras, gales and galea.
(n) :
Alternative form of galleass. [(nautical, historical) A type of rowable vessel of the 16th and 17th centuries, similar to a galley but larger, and normally equipped with sails.]
(n) :
Alternative form of galleass. [(nautical, historical) A type of rowable vessel of the 16th and 17th centuries, similar to a galley but larger, and normally equipped with sails.]