wide-brimmed hat with a conical crown worn in ancient Greece. The petasos worn by men had a rather low crown, while that worn by women had a tall one.

A hat used for traveling, the petasos was made of felt or straw and had a chin strap, so that when not in use it could be hung down the back. The winged hat of the god Hermes (or Mercury) was also called a petasos.