Opera hat described as: Some sources have taken this to describe an early folding top hat, although it is not explicitly stated whether Dollman's design was specifically for male or female headgear. Dollman's patent expired in 1825. Operating from Poissy, Paris, France, around 1840, Antoine Gibus's design for a spring-loaded collapsible top-hat proved so popular that hats made to it became known as "gibus". They were also often called "opera hats" due to the common practice of storing them in their flattened state under one's seat at the opera, though the term can also refer to any tall formal men's hat. The
Chapeau Some forms of bicorne were designed to be folded flat, so that they could be conveniently tucked underneath the arm when not being worn. A bicorne of this style is also known as a chapeau-bras or chapeau-de-bras (literally "arm-hat"). "Chapeau!" is often used as a generic expression of approval and appreciation in France and other parts of Europe: as a sign of admiration or respect, one shall indeed remove their hat. The expression is especially used as a sign of respect in the world of cycling, especially the Tour De France, as a way to show approval of a good