noun
three-cornered hat; tricorne
Refers to a hat with a brim turned up on three sides, historically worn in 18th-century Europe. Also called 三角帽 (さんかくぼう).
See also: 三角帽
あの絵の男は三角帽子をかぶっている。
The man in that painting is wearing a tricorne.
Synonym; 三角帽子 is slightly more common in everyday speech, while 三角帽 can sound more technical or historical.
Compound of 三角 (さんかく, 'triangle') and 帽子 (ぼうし, 'hat'). The term is a direct description of the hat's shape.