noun
Historical term for a woman in a recognized but secondary marital-like relationship, often in aristocratic or samurai contexts. Not used for modern extramarital affairs.
江戸時代、大名には正室のほかに侍妾がいることもあった。
In the Edo period, a daimyo sometimes had a concubine in addition to his legal wife.
Compound of 侍 (じ, 'to serve') and 妾 (しょう, 'concubine'), literally 'serving concubine'. The exact historical derivation is uncertain, but the spelling is conventionally associated with this meaning.