What can a wife call her husband's other wife in polygynous societies?
I am aware that two wives of the same man can be named co-wives. But what can a wife call her husband's other wife? I think calling her my co-wife will not be correct.
Sister wife.
(in a polygamous society) any of the women married to the same man.
‘her mother and her sister wives live in different homes’
Reference:
https://en.oxforddictionaries.com/definition/sister_wife