married couple; husband and wife
Archaic term for a married couple, often used in classical poetry and literature. Not used in modern everyday speech.
妹背の契りを交わす。
They exchange vows as husband and wife.
brother and sister; siblings
Archaic term for a brother and sister pair, especially in classical contexts. The word emphasizes the close bond between siblings.
妹背の仲睦まじい様子が描かれている。
The close relationship between the brother and sister is depicted.
Modern standard word for brother and sister, commonly used in contemporary Japanese.
wagtail (Motacillidae, excluding pipits) · lesser cuckoo (Cuculus poliocephalus)
Archaic kanji spelling; 妹 (younger sister) and 背 (back/stature, here representing the husband or brother) combine to express a close pair.
Variant archaic spelling using 兄 (elder brother) instead of 背; both forms are rare and found in classical texts.
A compound of ancient いも, “sister, wife, or beloved woman,” and せ, “brother, husband, or beloved man,” denoting a male-and-female pair or a pair of siblings.