noun
boater hat
A stiff straw hat with a flat crown and brim, often associated with summer and traditional school uniforms. The cross-reference to かんかん帽 suggests it is the same type of hat.
See also: かんかん帽
祖父の古い写真には、ボーターをかぶった若い男性が写っている。
In my grandfather's old photos, there is a young man wearing a boater hat.