'Legitimate' in the Bible

He went to his father's home in Ophrah and murdered his half-brothers, the seventy legitimate sons of Jerub-Baal, on one stone. Only Jotham, Jerub-Baal's youngest son, escaped, because he hid.

But you have attacked my father's family today. You murdered his seventy legitimate sons on one stone and made Abimelech, the son of his female slave, king over the leaders of Shechem, just because he is your close relative.