側室は英語で
concubine

英語の定義

側室
1. n. concubine

concubine
1. 名詞. 内縁の妻、内妻。
2. 名詞. 妾。
3. 名詞. 古代社会において、性的目的の女奴隷。
4. 名詞. 側室、一夫多妻制において正妻又は第一夫人以外の妻。

concubine
1. n. A sexual partner, especially a woman, to whom one is not or cannot be married.
2. n. A woman who lives with a man, but who is not a wife.
3. n. (chiefly historical) A slave-girl or woman, kept for instance in a harem, who is held for sexual service.