sister wife

Noun

sister-wife (plural sister-wives)

1. A woman who is simultaneously sister and wife to her spouse.
   • My Grecians shall victorious prove, By me led on to War, the Sister-Wife of Jove.1743, trans. Philip Francis, “Odes”, in Horace, volume III, iii, page 64
2. In a polygamous marriage, a woman who is simultaneously the sister and co-wife of another.
   • Enmities between sister-wives will [be,] from their having known each other too intimately all their lives, more unmannerly than where they are strangers to each other1853, quoted in Robert Cox, Sabbath Laws and Sabbath Duties, page 194
3. A co-wife in general.
   • Yüeh-niang and her sister-wives, all dressed in formal gowns, came out from inside to greet them and ushered them into the rear reception hall2006, Xiaoxiaosheng, trans. David Tod Roy, The plum in the golden vase, or, Chin P'ing Mei, page 21