noun
best man; groomsman; bridesmaid
Refers to a person who assists the bride or groom at a wedding ceremony. Can be used for either gender, though context often clarifies.
結婚式で、彼は友人の介添人を務めた。
He served as his friend's best man at the wedding.
花
The bride's bridesmaid wore a beautiful dress.
noun
Historical term for a person who assists a duelist, ensuring fair play and acting as a witness. Rare in modern usage outside historical contexts.
決闘の際、介添人は武器を確認する役目があった。
In a duel, the second had the role of checking the weapons.
Compound of 介添え (kaizoe, 'assistance, helping') + 人 (nin, 'person'). The exact historical derivation is uncertain, but the word is conventionally associated with the meaning of a person who provides support or assistance in formal settings.