Another name for a bicorne hat. The bicorne or bicorn (two-cornered/horned or twihorn) is a historical form of hat widely adopted in the 1790s as an item of uniform by European and American military and naval officers. It is now most readily associated with Napoléon Bonaparte but in practice most generals and staff officers of the Napoleonic period wore bicornes, and it survived as a widely worn full-dress headdress until at least 1914. (source)