'Grandson' in the Bible

In the eighth month of the second year of the reign of Darius, this message from the LORD came to Berechiah's son Zechariah, the grandson of Iddo the prophet:

On the twenty-fourth day of the eleventh month (the month Shebat) in the second year of the reign of Darius, this message from the LORD came to Berechiah's son Zechariah, the grandson of Iddo the prophet:

the [priestly] family of the house of Levi by itself and their wives by themselves; the family of Shimei [grandson of Levi] by itself and their wives by themselves;