Pileus (hat)

The pileus (Greek πῖλος – pilos, also pilleus or pilleum in Latin) was a brimless, felt cap worn in Ancient Greece and surrounding regions, later also introduced in Ancient Rome. The Greek πιλίδιον (pilidion) and Latin pilleolus were smaller versions, similar to a skullcap.

The pileus was especially associated with the manumission of slaves, who wore it upon their liberation. It became emblematic of liberty and freedom from bondage. During the classic revival of the 18th and 19th centuries in Europe it was widely confused with the Phrygian cap (a similarly conical cap but which has the point softened and pulled forward), which, in turn, appeared frequently on statuary and heraldic devices as a "liberty cap.".

The pileus (plis in Albanian), is very common in Albania and Kosovo even today.

The pilos (Greek: πῖλος, felt) was a common conical travelling hat in Illyria and Ancient Greece. The pilos is the brimless version of the petasos. It could be made of felt or leather. Pilos caps often identify the mythical twins, or Dioscuri, Castor and Pollux, as represented in sculptures, bas-reliefs and on ancient ceramics. Their caps were supposedly the remnants of the egg from which they hatched. The pilos appears on votive figurines of boys at the sanctuary of the Cabeiri at Thebes, the Cabeirion.

In warfare, the pilos type helmet was often worn by the peltast light infantry, in conjunction with the exomis, but it was also worn by the heavy infantry.

...
Wikipedia