'Father in law' in the Bible

Now his daughter-in-law, the wife of Phinehas, [was] pregnant and [about] to give birth. When she heard the news concerning the capture of the ark of God and that her father-in-law and her husband had died, she {went into labor} and gave birth, because her labor pains came upon her.

She called the boy Ichabod, saying, "The glory has departed from Israel," referring to the capture of the ark of God and concerning her father-in-law and husband.