A petasos is a style of hat, usually made of wool felt, leather or straw, with a broad, floppy brim. It was worn primarily by farmers and travellers in classical times, and was considered characteristic of rural people. The name is the Greek and Latin word for any hat. The pilos is the brimless version of the petasos.
Representations of the Classical god Mercury (mythology) are frequently identified by a petasos, which he often wears. His petasos usually has little wings attached.