the world > textiles and clothing > clothing > types or styles of clothing > headgear > [noun] > hat > which can be crushed flat (3)
a hat suitable for use at the opera; spec. a man's tall collapsible hat.
A soft hat which can be crushed flat; spec. a hat constructed with a spring so as to collapse and assume a flat shape; an opera-hat.
An opera or crush hat. Also gibus-hat.