Okay kiddo, so have you ever seen a painting of a woman with a little band across her forehead with a jewel in the middle? That's called a ferronnière!
Basically, a ferronnière is a type of headband that was popular in the Renaissance era. It was worn by women and consisted of a small ribbon or band that went around the forehead and had a jewel or ornament in the center.
The name "ferronnière" comes from an Italian phrase that means "iron-worker's wife." It's said that this kind of headband was originally worn by the wives of iron workers in Italy, but it became fashionable among women of all social classes in the Renaissance.
If you ever see a painting from that time period with a lady wearing this type of headband, just remember that it's called a ferronnière!