illegitimate child; born to a mistress
Rare, formal term for a child born out of wedlock, specifically to a mistress. Not used in everyday conversation; modern Japanese prefers 非嫡出子 or 婚外子.
In old documents, the expression 'child of a mistress' can be found.
Compound of 妾 (mistress) and 出 (come out, be born). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning of illegitimate birth.