'Father in law' in the Bible

Eli's daughter-in-law, the wife of Phineas, was pregnant and ready to give birth. When she heard the report about the capture of the Ark of God and that her father-in-law and husband were dead, she crouched down and gave birth, because her labor pains suddenly began.

She had named the boy Ichabod,saying, "Glory has departed from Israel," because the Ark of God had been captured and because her father-in-law and husband were dead.