'Sister in law' in the Bible

But if the man [does] not want to take his sister-in-law, then his sister-in-law shall go up to the gate, to the elders, and she shall say, 'My brother-in-law refused {to perpetuate his brother's name} in Israel, [for] he is not willing {to marry me}.'

then his sister-in-law must approach him in view of the elders, remove his sandal from his foot, and spit in his face. She will then respond, "Thus may it be done to any man who does not maintain his brother's family line!"

Naomi told Ruth, "Look, your sister-in-law has returned to her people and to her gods. Follow your sister-in-law!"

Pharaoh liked Hadad so well he gave him his sister-in-law (Queen Tahpenes' sister) as a wife.