Fillet hats originated from Mediterranean cultures and evolved into a headband that unmarried women and celibate nuns wore. The cap had a crown shape that was narrower at the bottom and broader at the top. The hat was perfectly circular and supported by a barbette or a chin band to keep it stable.
Sometimes, the hat would even have a short veil at the back to make it look a lot more stylish and conservative. The fillet is, at times, confused as a material; however, it is the wrapping style of cloth. It is a single cloth wrapped first around the chin and head vertically and then around the head horizontally and pinned at the back of the head.