'Father in law' in the Bible

Eli’s daughter-in-law, the wife of Phinehas, was pregnant and about to give birth. When she heard the news about the capture of God’s ark and the deaths of her father-in-law and her husband, she collapsed and gave birth because her labor pains came on her.

She named the boy Ichabod, saying, “The glory has departed from Israel,” referring to the capture of the ark of God and to the deaths of her father-in-law and her husband.