illegitimate family lineage; branch family of illegitimate descent
Historical term referring to a family line descended from a concubine or illegitimate child, as opposed to the main legitimate line (嫡流). Used in contexts of samurai clans and noble houses.
He was from an illegitimate branch of the family, but he succeeded the house through his own ability.
戦国時代には、庶流が嫡流をしのぐこともあった。
During the Warring States period, illegitimate branches sometimes surpassed the main line.