forehead eboshi; black triangle worn on forehead
A small black silk or paper triangle worn over the forehead, traditionally by children as part of festival or ceremonial attire.
During the festival, the children danced wearing forehead eboshi.
A broader term for a type of traditional Japanese headgear; 額烏帽子 specifically refers to the small triangular piece worn on the forehead.
Compound of 額 (ひたい, 'forehead') and 烏帽子 (えぼし, 'eboshi', a traditional court cap). The exact historical derivation is uncertain; the term describes a small triangular piece worn on the forehead, resembling a miniature eboshi.