/pet"euh seuhs/ , n. , pl. petasuses .
a broad-brimmed hat worn by ancient Greek travelers and hunters, often represented in art as a winged hat worn by Hermes or Mercury.
Also, petasos /pet"euh seuhs, -sos'/ .
[ 1590-1600; pétasos, akin to petannýnai to spread out ]