We don't have synonyms for petasus yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are pegasus and petasos.
(n) :
(historical) A broad-brimmed, low-crowned hat worn by the Ancient Greeks and Romans, especially for travelling, and as often pictured to be worn by Hermes (or Mercury); (later also) the brimless winged cap worn by Hermes in later artistic depictions.
(n) :
(historical) A broad-brimmed, low-crowned hat worn by the Ancient Greeks and Romans, especially for travelling, and as often pictured to be worn by Hermes (or Mercury); (later also) the brimless winged cap worn by Hermes in later artistic depictions.